This is the definition of \chaptermark
in report.cls
for the headings
page style (one sided):
\def\chaptermark#1{%
\markright {\MakeUppercase{%
\ifnum \c@secnumdepth >\m@ne
\@chapapp\ \thechapter. \ %
\fi
#1}}}
Your needs seem to be twofold: "KAPITEL 1." bold and the chapter title medium face. There's also the definition of \@oddhead
to keep in mind:
\def\@oddhead{{\slshape\rightmark}\hfil\thepage}%
We have to change the way both commands act:
\makeatletter
\def\chaptermark#1{%
\markboth {\MakeUppercase{%
{\bfseries\ifnum \c@secnumdepth >\m@ne
\@chapapp\ \thechapter.} \ %
\fi
#1}}{}}
\def\@oddhead{\rightmark\hfil\thepage}
\newcommand\tableofcontents{%
\if@twocolumn
\@restonecoltrue\onecolumn
\else
\@restonecolfalse
\fi
\chapter*{\contentsname
\@mkboth{%
{\bfseries\MakeUppercase\contentsname}}
{{\bfseries\MakeUppercase\contentsname}}}%
\@starttoc{toc}%
\if@restonecol\twocolumn\fi
}
\makeatother
A similar adjustment should be done also to the definition of thebibliography
and theindex
(if you use them).
`
to mark your inline code.