[Tex/LaTex] How to set the font for a \section title (and chapter etc)

fontsfontsizesectioningtitlesec

How do I specify the fonts, and general font size, for the titles, chapters and sections in my document

Update:

I can see how my question is confusing.

I use \section and \chapter etc. to organise my document, and I would like to change the way the section and chapter titles are displayed.

For the standard classes titlesec would be my choice. Here's an example using titlesec and the standard formatting/spacing, except that the font is changed to Helvetica (Arial has been derived from it) and the font color for demonstration. Adjust the \titleformat arguments to achieve what you desire.

\documentclass{report}
\usepackage[english]{babel}
\usepackage{blindtext}
\usepackage{mathptmx}% Times Roman font
\usepackage[scaled=.90]{helvet}% Helvetica, served as a model for arial
\usepackage{xcolor}
\usepackage{titlesec}
\titleformat{\chapter}[display]
{\normalfont\sffamily\huge\bfseries\color{blue}}
{\chaptertitlename\ \thechapter}{20pt}{\Huge}
\titleformat{\section}
{\normalfont\sffamily\Large\bfseries\color{cyan}}
{\thesection}{1em}{}
\begin{document}
\Blinddocument
\end{document}


With KOMA-Script classes it's easy as many other issues, just use \setkomafont and \addtokomafont. Here's the example:

\documentclass{scrreprt}
\usepackage[english]{babel}
\usepackage{blindtext}
\usepackage{mathptmx}% Times Roman font
\usepackage[scaled=.90]{helvet}% Helvetica, served as a model for arial
\usepackage{xcolor}
\usepackage{titlesec}
\setkomafont{chapter}{\normalfont\huge\sffamily\bfseries\color{blue}}