Customize Both Chapter Style and Headings

Question

I'am using memoir. With these basic settings:

\makechapterstyle{chappell2}{%
\setlength{\beforechapskip}{-15pt}
\renewcommand*{\chapnamefont}{\large}

\renewcommand*{\printchapternum}{\chapnumfont \Large \thechapter }
\renewcommand*{\chaptitlefont}{\Large\bfseries}
\renewcommand*{\printchaptertitle}[1]{%
%\vskip\onelineskip 
\chaptitlefont ##1}}

\makechapterstyle{mystyle}{%
    \chapterstyle{default}
    \renewcommand{\printchaptername}{}
    \renewcommand{\chapternamenum}{}
    \renewcommand{\chapnumfont}{\normalfont\bfseries}
    \renewcommand{\printchapternum}{}%\chapnumfont \thechapter\space}
    \renewcommand{\afterchapternum}{}
    \renewcommand*{\printchapternum}{%
    \@hangfrom{\chapnumfont \thechapter\quad}}%
}
%\nouppercaseheads

\chapterstyle{chappell2}
\renewcommand\thechapter{Capitolo \arabic{chapter}}
\renewcommand\thesection{\arabic{section}}
\renewcommand\thesubsection{\thesection.\arabic{subsection}}
\renewcommand\thesubsubsection{\thesubsection\arabic{subsubsection}}

I get this:

I would like to print in the heading only "Capitolo 2". How can I do it? Sorry, but I'am not an expert in latex...

Answer 1

You did not provide a compilable example which must start from \documentclass... through to \end{document}. What you did provide when I added the necessary code did not produce what you showed in your graphic.

I have done my best and I think that this is what might suit you.

\documentclass{memoir}
\usepackage{lipsum}

\renewcommand{\chaptername}{Capitolo}  % change chapter name
\renewcommand{\chapterrefname}{Capitolo} % change chapter reference name  
\makechapterstyle{chappell2}{%
\setlength{\beforechapskip}{-15pt}
%\renewcommand*{\chapnamefont}{\large}
\renewcommand*{\chapnamefont}{\Large\bfseries} % to match the chapter number

\renewcommand*{\printchapternum}{\chapnumfont \Large \thechapter }
\renewcommand*{\chaptitlefont}{\Large\bfseries}
\renewcommand*{\printchaptertitle}[1]{%
%\vskip\onelineskip 
\chaptitlefont ##1}}

%\nouppercaseheads

\chapterstyle{chappell2}
%\renewcommand\thechapter{Capitolo \arabic{chapter}}
\renewcommand\thesection{\arabic{section}}
\renewcommand\thesubsection{\thesection.\arabic{subsection}}
\renewcommand\thesubsubsection{\thesubsection\arabic{subsubsection}}

\begin{document}

\frontmatter
\tableofcontents
\mainmatter
\chapter{INFORMAZIONI}
\lipsum[1]
\section{First section}
\lipsum
\chapter{ANOTHER}
\lipsum[2]
\end{document}

You defined a mystyle chapterstyle but did not use it. Why?