How to change bibliography style for all authors?

Question

I am using the mastersdoctoral thesis template from http://www.LaTeXTemplates.com. The bibliography appears with Author et al., both in text and in bibliography section for more than 4 authors, while for 3 or fewer authors all names are written out. I want to have Author et al. for more than 3 in the text and whole author list in the bibliography section. Any suggestions? Thanks in advance.

My preamble (not much modified from original template):

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Masters/Doctoral Thesis 
% LaTeX Template
% Version 2.5 (27/8/17)
%
% This template was downloaded from:
% http://www.LaTeXTemplates.com
%
% Version 2.x major modifications by:
% Vel (vel@latextemplates.com)
%
% This template is based on a template by:
% Steve Gunn (http://users.ecs.soton.ac.uk/srg/softwaretools/document/templates/)
% Sunil Patel (http://www.sunilpatel.co.uk/thesis-template/)
%
% Template license:
% CC BY-NC-SA 3.0 (http://creativecommons.org/licenses/by-nc-sa/3.0/)
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%----------------------------------------------------------------------------------------
%   PACKAGES AND OTHER DOCUMENT CONFIGURATIONS
%----------------------------------------------------------------------------------------

\documentclass[
11pt, % The default document font size, options: 10pt, 11pt, 12pt
%oneside, % Two side (alternating margins) for binding by default, uncomment to switch to one side
english, % ngerman for German
onehalfspacing, % Single line spacing, alternatives: onehalfspacing or doublespacing
%draft, % Uncomment to enable draft mode (no pictures, no links, overfull hboxes indicated)
%nolistspacing, % If the document is onehalfspacing or doublespacing, uncomment this to set spacing in lists to single
liststotoc, % Uncomment to add the list of figures/tables/etc to the table of contents
%toctotoc, % Uncomment to add the main table of contents to the table of contents
%parskip, % Uncomment to add space between paragraphs
%nohyperref, % Uncomment to not load the hyperref package
headsepline, % Uncomment to get a line under the header
%chapterinoneline, % Uncomment to place the chapter title next to the number on one line
%consistentlayout, % Uncomment to change the layout of the declaration, abstract and acknowledgements pages to match the default layout
]{MastersDoctoralThesis} % The class file specifying the document structure
\usepackage[utf8]{inputenc} % Required for inputting international characters
\usepackage[T1]{fontenc} % Output font encoding for international characters

\usepackage{mathpazo} % Use the Palatino font by default
%\usepackage[]{natbib}
\usepackage[backend=bibtex8,style=authoryear,natbib=true]{biblatex} % Use the bibtex backend with the authoryear citation style (which resembles APA)

\addbibresource{thesis.bib} % The filename of the bibliography

\usepackage[autostyle=true]{csquotes} % Required to generate language-dependent quotes in the bibliography
\usepackage[Sonny]{fncychap}
\usepackage{setspace}
\usepackage{float}
\usepackage{morefloats}
\usepackage{ifpdf}
\raggedbottom        
\usepackage{multicol}
\usepackage[demo]{rotating}

\usepackage{titlesec} 
\titleformat{\subsection}[block]{\large}{\thesubsection.}{1em}{}
\usepackage{subfigure}
\usepackage{setspace}
\usepackage{bm}      
%math equations
\let\proof\relax
\let\endproof\relax
\usepackage{amsmath,amssymb,amsthm}
\usepackage{amsfonts}
\usepackage{listings}
\usepackage{inputenc}
%\usepackage[usenames,dvipsnames]{xcolor}
\usepackage{hyperref}
\hypersetup{citecolor=blue,colorlinks=true,linkcolor=black}


%%---------------------------------------------------------------------------------------
%   MARGIN SETTINGS
%----------------------------------------------------------------------------------------

\geometry{
    paper=a4paper, % Change to letterpaper for US letter
    inner=3.2cm, % Inner margin
    outer=2.6cm, % Outer margin
    bindingoffset=.5cm, % Binding offset
    top=1.5cm, % Top margin
    bottom=1.5cm, % Bottom margin
    %showframe, % Uncomment to show how the type block is set on the page
}

%----------------------------------------------------------------------------------------
%   THESIS INFORMATION
%----------------------------------------------------------------------------------------

\thesistitle{Bn } % Your thesis title, this is used in the title and abstract, print it elsewhere with \ttitle
\supervisor{Prof. Dr. N  \textsc{Top}} % Your supervisor's name, this is used in the title page, print it elsewhere with \supname
\examiner{} % Your examiner's name, this is not currently used anywhere in the template, print it elsewhere with \examname
\degree{Doctor of Philosophy} % Your degree name, this is used in the title page and abstract, print it elsewhere with \degreename
\author{Neon \textsc{Light}} % Your name, this is used in the title  page and abstract, print it elsewhere with \authorname
\addresses{} % Your address, this is not currently used anywhere in the template, print it elsewhere with \addressname

\subject{Immunology} % Your subject area, this is not currently used anywhere in the template, print it elsewhere with \subjectname
\keywords{} % Keywords for your thesis, this is not currently used anywhere in the template, print it elsewhere with \keywordnames
\university{\href{http://www.google.com}{B B}} % Your university's name and URL, this is used in the title page and abstract, print it elsewhere with \univname
\department{\href{http://www.google.com}{Department of Sciences}} % Your department's name and URL, this is used in the title page and abstract, print it elsewhere with \deptname
\group{\href{http://www.google.com}{N N }} % Your research group's name and URL, this is used in the title page, print it elsewhere with \groupname
\faculty{\href{http://www.google.com}{Faculty of Sci}} % Your faculty's name and URL, this is used in the title page and abstract, print it elsewhere with \facname

\AtBeginDocument{
    \hypersetup{pdftitle=\ttitle} % Set the PDF's title to your title
    \hypersetup{pdfauthor=\authorname} % Set the PDF's author to your name
    \hypersetup{pdfkeywords=\keywordnames} % Set the PDF's keywords to your keywords
}

\begin{document} 

    \frontmatter % Use roman page numbering style (i, ii, iii, iv...) for the pre-content pages

    \pagestyle{plain} % Default to the plain heading style until the thesis style is called for the body content

    %----------------------------------------------------------------------------------------
    %   TITLE PAGE
    %----------------------------------------------------------------------------------------

    \begin{titlepage}
        \begin{center}

            \vspace*{.06\textheight}
            {\scshape\LARGE \univname\par}\vspace{1.5cm} % Universiteit Utrecht
            \textsc{\Large Doctoral Thesis}\\[0.5cm] % Thesis type

            \HRule \\[0.4cm] % Horizontal line
            {\huge \bfseries \ttitle\par}\vspace{0.4cm} % Thesis title
            \HRule \\[1.5cm] % Horizontal line

            \begin{minipage}[t]{0.4\textwidth}
                \begin{flushleft} \large
                    \emph{Author:}\\
                    {\authorname} % Author name - remove the \href bracket to remove the link
                \end{flushleft}
            \end{minipage}
            \begin{minipage}[t]{0.4\textwidth}
                \begin{flushright} \large
                    \emph{Supervisor:} \\
                    {\supname} % Supervisor name - remove the \href bracket to remove the link  
                \end{flushright}
            \end{minipage}\\[3cm]

            \vfill
            %\centering
            %\includegraphics{logo}
            \large \textit{A thesis submitted in fulfilment of the requirements\\ for the degree of \degreename}\\[0.3cm] % University requirement text
            \textit{in the}\\[0.4cm]
            \groupname\\\deptname\\[2cm] % Research group name and department name

            \vfill

            {\large \today}\\[4cm] % Date
            %\includegraphics{Logo} % University/department logo - uncomment to place it

            \vfill
        \end{center}
    \end{titlepage}

    %----------------------------------------------------------------------------------------
    %   DECLARATION PAGE
    %----------------------------------------------------------------------------------------

    \begin{declaration}
        \addchaptertocentry{\authorshipname} % Add the declaration to the table of contents
        \noindent I, \authorname, declare that this thesis titled, \enquote{\ttitle} and the work presented in it are my own. I confirm that:

        \begin{itemize} 
            \item This work was done wholly or mainly while in candidature for a research degree at this University.
            \item Where any part of this thesis has previously been submitted for a degree or any other qualification at this University or any other institution, this has been clearly stated.
            \item Where I have consulted the published work of others, this is always clearly attributed.
            \item Where I have quoted from the work of others, the source is always given. With the exception of such quotations, this thesis is entirely my own work.
            \item I have acknowledged all main sources of help.
            \item Where the thesis is based on work done by myself jointly with others, I have made clear exactly what was done by others and what I have contributed myself.\\
        \end{itemize}

        \noindent Signed:\\
        \rule[0.5em]{25em}{0.5pt} % This prints a line for the signature

        \noindent Date:\\
        \rule[0.5em]{25em}{0.5pt} % This prints a line to write the date
    \end{declaration}

    \cleardoublepage

    %----------------------------------------------------------------------------------------
    %   QUOTATION PAGE
    %----------------------------------------------------------------------------------------

    \vspace*{0.2\textheight}

    \noindent\enquote{\itshape }\bigbreak

    \hfill 

    %----------------------------------------------------------------------------------------
    %   ABSTRACT PAGE
    %----------------------------------------------------------------------------------------
\begin{abstract}
\addchaptertocentry{\abstractname} % Add the abstract to the table of contents

 The problem can be seen when using this citation: \citep{FiPrWuCa89}, it will appear as 
 Fink et al. 1989 in the text as well as in the bibliography. 
 While this one: \citep{GaMaNaHelene} will appear as a list of all names in both places.



\end{abstract}
\clearpage

\addchaptertocentry{\abstractname} % Add the abstract to the table of contents




    %----------------------------------------------------------------------------------------
    %   ACKNOWLEDGEMENTS
    %----------------------------------------------------------------------------------------

    \begin{acknowledgements}
        \addchaptertocentry{\acknowledgementname} % Add the acknowledgements to the table of contents
        The acknowledgements and the people to thank go here, don't forget to include your project advisor\ldots
    \end{acknowledgements}

    %----------------------------------------------------------------------------------------
    %   LIST OF CONTENTS/FIGURES/TABLES PAGES
    %----------------------------------------------------------------------------------------

    \tableofcontents % Prints the main table of contents

    \listoffigures % Prints the list of figures

    \listoftables % Prints the list of tables

    %----------------------------------------------------------------------------------------
    %   ABBREVIATIONS
    %----------------------------------------------------------------------------------------

    \begin{abbreviations}{ll} % Include a list of abbreviations (a table of two columns)



    \end{abbreviations}

%----------------------------------------------------------------------------------------
%   SYMBOLS
%----------------------------------------------------------------------------------------

        \begin{symbols}{lll} % Include a list of Symbols (a three column table)



%       \addlinespace % Gap to separate the Roman symbols from the Greek
% 
%         $\omega$ & angular frequency & \si{\radian} \\

        \end{symbols}

    %----------------------------------------------------------------------------------------
    %%  DEDICATION
    %----------------------------------------------------------------------------------------

    %\dedicatory{For/Dedicated to/To my\ldots} 

    %----------------------------------------------------------------------------------------
    %   THESIS CONTENT - CHAPTERS
    %----------------------------------------------------------------------------------------

    \mainmatter % Begin numeric (1,2,3...) page numbering
    \ohead*{}
    \ofoot*{\pagemark}
    \pagestyle{thesis} % Return the page headers back to the "thesis" style

    % Include the chapters of the thesis as separate files from the Chapters folder
    % Uncomment the lines as you write the chapters

    %\include{Chapters/Chapter1}
    %\include{Chapters/Chapter2} 
    %\include{Chapters/Chapter3}
    %\include{Chapters/Chapter4} 
    %\include{Chapters/Chapter5} 
    %\include{Chapters/Chapter6} 
    %\include{Chapters/Chapter7} 


    %----------------------------------------------------------------------------------------
    %   THESIS CONTENT - APPENDICES
    %----------------------------------------------------------------------------------------

    %\appendix % Cue to tell LaTeX that the following "chapters" are Appendices

    % Include the appendices of the thesis as separate files from the Appendices folder
    % Uncomment the lines as you write the Appendices  

    %\include{Appendices/AppendixA}
    %\include{Appendices/AppendixB}
    %\include{Appendices/AppendixC}




    %----------------------------------------------------------------------------------------
    %   BIBLIOGRAPHY
    %----------------------------------------------------------------------------------------

    \printbibliography 

    %----------------------------------------------------------------------------------------

\end{document}