Fancyhdr: unwanted different header fonts in ToC and normal text

The header font in my ToC is different than the header font in the document. How can I change that?

\documentclass[a4paper,12pt]{scrreprt}

\usepackage[ngerman]{babel}
\usepackage{color,
mathptmx,
fancyhdr,tikz}

\definecolor{myblue}{rgb} {0,0,0}%{0.15,0.15,0.25}

\newcommand{\changefont}[3]{
\fontfamily{#1} \fontseries{#2} \fontshape{#3} \selectfont}

\pagestyle{fancy}
\fancyfoot{}
}

\begin{document}

\tableofcontents

\chapter{Testchapter}
\section{Testsection}
%several chapters and sections

\end{document}


Please have a look at the picture below... Thank you!

Maybe it is better to use scrlayer-scrpage. This package is also part of the KOMA-Script bundle:

\documentclass[12pt]{scrreprt}

\usepackage[ngerman]{babel}
\usepackage{mathptmx}
\usepackage{microtype}
\usepackage{xcolor}

\definecolor{myblue}{rgb}{0,0,0}%{0.15,0.15,0.25}

\usepackage[
automark,
markcase=upper
]{scrlayer-scrpage}
\clearpairofpagestyles