I am asking almost the same question as link for similar questions
I want to have
Smith (1998 & 1999)
However, for this question, i added
style=authoryear-comp.
and
\renewcommand{\compcitedelim}{\space\&\space}
to my MWE, is not working
It might be because of
citestyle=authoryear
\RequirePackage{filecontents}
\begin{filecontents}{\jobname.bib}
@article{journal1,
title={title ABC},
author={Smith, Bether},
journal={Behavior Research Methods, Instruments, \& Computers},
volume={24},
number={2},
pages={258--264},
year={1992},
publisher={Springer}
}
@article{journal2,
title={title CBD},
author={Smith, Bether},
journal={Behavior Research Methods, Instruments, \& Computers},
volume={25},
number={2},
pages={242--249},
year={1993},
publisher={Springer}
}
@article{journal2,
title={journal123456},
author={Abc, Def, GhI},
journal={Journal of Neurology, Neurosurgery \& Psychiatry},
volume={62},
number={1},
pages={22--26},
year={1999},
}
\end{filecontents}
\documentclass[british]{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{babel}
\usepackage{csquotes}
\usepackage[%
style=authoryear,
style=authoryear-comp,
backend=biber,
maxcitenames=2,
giveninits,
dashed=false,
citestyle=authoryear,
]{biblatex}
\addbibresource{\jobname.bib} % \jobname to use the bib file created with filecontents
\usepackage[unicode,colorlinks,citecolor=blue]{hyperref}
\DeclareNameAlias{sortname}{family-given} %for second and third author name
% for references 's studies (year)
\renewcommand*{\nameyeardelim}{\addcomma\space}
\newcommand{\mycite}[1]{\citeauthor{#1}'s \citeyear{#1}}
% for combine both year for an author
\DeclareDelimFormat{nameyeardelim}{\addcomma\space}
\renewcommand{\compcitedelim}{\space\&\space}
\DeclareCiteCommand{\citeauthor}
{\boolfalse{citetracker}%
\boolfalse{pagetracker}%
\usebibmacro{prenote}}
{\ifciteindex
{\indexnames{labelname}}
{}%
\printtext[bibhyperref]{\printnames{labelname}}}
{\multicitedelim}
{\usebibmacro{postnote}}
\DeclareCiteCommand{\citeyear} % <======================================
{}
{(\bibhyperref{\printdate})}
{\multicitedelim}
{}
\DeclareCiteCommand{\parencite}[\mkbibparens]
{\usebibmacro{prenote}}
{\usebibmacro{citeindex}%
\printtext[bibhyperref]{\usebibmacro{cite}}}
{\multicitedelim}
{\usebibmacro{postnote}}
\makeatletter
\let\abx@macro@textciteOrig\abx@macro@textcite
\renewbibmacro{textcite}{% <============================================
\bibhyperref{%
\let\bibhyperref\relax\relax%
\abx@macro@textciteOrig%
}%
}%
\makeatother
% for references 's studies (year)
\begin{document}
ABC studies is done by \textcite{journal1, journal2}.
\printbibliography
\end{document}

citestyle=authoryear, the\parencite{}is not working. It needcitestyle=authoryear– aan Sep 13 '19 at 00:41\usebibmacro{cite:init}from your redefinition of\parencite. Look inauthoryear-comp.cbxfor the default definition. – David Purton Sep 13 '19 at 00:53Smith (1998), 1999)which is wrong. – aan Sep 13 '19 at 01:51biblatexon overleaf is too old. I don't know which. You'll have to work backwards, cutting out customisations one by one until you know where the problem is. – David Purton Sep 13 '19 at 01:57biblatex? – aan Sep 13 '19 at 01:59biblatexis 3.13. You can add\listfilesat the top of any document and the log file will show you the version in use. – David Purton Sep 13 '19 at 02:02(redefination parencite, style)I posted this question in https://tex.stackexchange.com/questions/508112/i-had-customisations-my-biblatex-result-is-smith-1992-1993-it-suppose-sm – aan Sep 13 '19 at 02:20\parencitedefinition that you rightly point out as problematic is discussed in https://tex.stackexchange.com/q/546403/35864. The\printtextin that position completely confuses the punctuation buffer. – moewe May 27 '20 at 06:19