In your preamble, add these lines
\DeclareNameAlias{sortname}{given-family-bold}
\DeclareNameFormat{given-family-bold}{\mkbibbold{%
\ifgiveninits
{\usebibmacro{name:given-family}{\namepartfamily}{\namepartgiveni}
{\namepartprefix}{\namepartsuffix}}
{\usebibmacro{name:given-family}{\namepartfamily}{\namepartgiven}
{\namepartprefix}{\namepartsuffix}}%
\usebibmacro{name:andothers}}}
The MWE
\documentclass[12pt,a4paper]{report}
\usepackage{lipsum}
\usepackage[backend=biber,style=authoryear,citestyle=apa]{biblatex}
\usepackage{filecontents}
\begin{filecontents}{\jobname.bib}
@Book{test1,
author = {Goossens, Michel and Mittelbach, Frank and Samarin, Alexander},
title = {The LaTeX Companion},
publisher = {Addison-Wesley},
location = {Reading, Mass.},
year = {1994},
}
\end{filecontents}
\addbibresource{\jobname.bib}
\DeclareNameAlias{sortname}{given-family-bold}
\DeclareNameFormat{given-family-bold}{\mkbibbold{%
\ifgiveninits
{\usebibmacro{name:given-family}{\namepartfamily}{\namepartgiveni}{\namepartprefix}{\namepartsuffix}}
{\usebibmacro{name:given-family}{\namepartfamily}{\namepartgiven}{\namepartprefix}{\namepartsuffix}}%
\usebibmacro{name:andothers}}}
\begin{document}
\chapter{Test}
Test paragraph, just random words \parencite{test1}. \lipsum[1-2]
\setlength\bibitemsep{10pt}
\printbibliography
\end{document}
As the OP wants the bibliography to be sorted lastname, firstname, firstname lastname and firstname lastname, as @moewe pointed out in https://tex.stackexchange.com/a/178877/35864 -- these lines should go in the preamble.
\DeclareNameAlias{sortname}{family-given/given-family-bold}
\DeclareNameFormat{family-given/given-family-bold}{\mkbibbold{%
\ifnumequal{\value{listcount}}{1}
{\ifgiveninits
{\usebibmacro{name:family-given}
{\namepartfamily}
{\namepartgiveni}
{\namepartprefix}
{\namepartsuffix}}
{\usebibmacro{name:family-given}
{\namepartfamily}
{\namepartgiven}
{\namepartprefix}
{\namepartsuffix}}%
\ifboolexpe{%
test {\ifdefvoid\namepartgiven}
and
test {\ifdefvoid\namepartprefix}}
{}
{\usebibmacro{name:revsdelim}}}
{\ifgiveninits
{\usebibmacro{name:given-family}
{\namepartfamily}
{\namepartgiveni}
{\namepartprefix}
{\namepartsuffix}}
{\usebibmacro{name:given-family}
{\namepartfamily}
{\namepartgiven}
{\namepartprefix}
{\namepartsuffix}}}%
\usebibmacro{name:andothers}}}
\addcontentslineafter\printbibliographywould add the last page of the bibliography to the ToC not the first. Seebibintocin thebiblatexmanual for information about how to add the bibliography into the ToC. – Schweinebacke Sep 04 '17 at 09:17style=authoryear, citestyle=apais neither here nor there. A document like this will not conform with APA style. Does onlystyle=authoryearnot give you what you need? – moewe Sep 04 '17 at 12:24\DeclareFieldFormat{parens}{\bfseries{\mkbibparens{#1}}}will potentially make much more bold than just the parentheses around the year. It will make all parentheses typeset bybiblatexbold. – moewe Sep 04 '17 at 13:13