LaTeX Forum

\documentclass[a4paper,fontsize=12pt,headsepline, bibliography=totocnumbered, captions=nooneline]{scrartcl}

\usepackage[german]{babel}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{scrlayer-scrpage}
\automark{section}
\clearpairofpagestyles
\setkomafont{pagehead}{\sffamily\small\upshape}
\ohead{\headmark}
\ofoot*{\pagemark}
\usepackage{csquotes}
\usepackage[style=apa, backend=biber]{biblatex}
\urlstyle{same}
\DeclareLanguageMapping{ngerman}{ngerman-apa}
\addbibresource{Literatur3.bib}

\begin{document} 
\sffamily
\setkomafont{section}{\large\sffamily}
\setkomafont{subsection}{\normalsize\sffamily}
\addtokomafont{captionlabel}{\sffamily}
\setkomafont{caption}{\sffamily}
Hallo\parencite{str15}
Tschüss\parencite{kue16.1}
\printbibliography

\end{document}

\documentclass[fontsize=12pt,headsepline, bibliography=totocnumbered, captions=nooneline]{scrartcl}

\usepackage[ngerman]{babel}% <- geändert
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{lmodern}% <- eingefügt
\usepackage{scrlayer-scrpage}
\usepackage{csquotes}
\usepackage[style=apa]{biblatex}

% Lies im fünften Abschnitt von biblatex-apa.pdf, ob Du den Befehl noch brauchst.
\DeclareLanguageMapping{ngerman}{ngerman-apa}

\addbibresource{biblatex-examples.bib}

\automark{section}
\clearpairofpagestyles
\ohead{\headmark}
\ofoot*{\pagemark}
\urlstyle{same}

% Änderungen
\setkomafont{pagehead}{\small\upshape}
\setkomafont{section}{\large}
\setkomafont{subsection}{\normalsize}
%\addtokomafont{captionlabel}{\sffamily}
%\setkomafont{caption}{\sffamily}

\renewcommand{\familydefault}{\sfdefault}% Ersatz für \sffamily

\begin{document}
\captionof{figure}{Abbildungsbeschriftung}

\parencite{herrmann}
\printbibliography
\end{document}