Remove chapter name from header

Question

I am writing a document in the report class (for a number of reasons). I want a custom header for all pages, except the cover. I have managed to do so, the only problem is that I can't take off the Chapter name of the headings.

So far, this is my approach so far:

\documentclass[12p]{report}
\usepackage{arabtex}
\usepackage[utf8]{inputenc}
\usepackage[T2A,LAE,T1]{fontenc}
\usepackage{utf8}
\setcode{utf8}
\usepackage{ae}
\usepackage{aecompl}
\usepackage[T1]{fontenc}
\usepackage[frenchb]{babel}
\usepackage{graphicx}
\usepackage{fancyhdr}
\usepackage{geometry}
\usepackage[dvipsnames]{xcolor}
\usepackage{mdframed}
\usepackage{fancybox}
\usepackage{adjustbox}
\usepackage{enumitem}
\usepackage{bbding}
\usepackage{tikz}
\usepackage{setspace}
\usepackage{csquotes} 
\usepackage{sectsty}
\usepackage{tikz, blindtext}
\usepackage{float}
\usepackage{caption}
\usepackage{wrapfig}
\usepackage{listings}
\usepackage{lipsum}

\definecolor{myblue}{RGB}{100,127,255}


\usepackage{titlesec}
\fancypagestyle{plain}
{\chead{\includegraphics[width=\textwidth]{forestfloor.jpg} \\ 
\textcolor{myblue}{Whatever} \\ BLA BLA BLA}}
\pagestyle{plain}

\pagestyle{fancyplain}

\begin{document}

\chapter{One}

\lipsum[1-15]

\chapter{Two}

\lipsum[1-15]

\end{document}

Can you help me please? To better understanding, this is a current output and marked what I DON'T want

Answer 1

Since you load titlesec, it has a titleps companion package, loaded by the pagestyles option, which makes it very easy, with the help of the stackenginepackage. As your header is quite high, I had to set some parameters of thegeometrypackage to remove error messages. Note thatfancyhdrandtitleps` are incompatible.

Unrelated: since version 3.10, language options for babel should be loaded with the document class, so that all language-dependent packages be informed. Also, packages ae and aecompl are obsolete and no more necessary.

\documentclass[12pt, french]{report}
\usepackage{arabtex}
\usepackage[utf8]{inputenc}
\usepackage[T2A,LAE,T1]{fontenc}
\usepackage{utf8}
\setcode{utf8}
%\usepackage{ae}%% obsolete
%\usepackage{aecompl}%% obsolete
\usepackage[T1]{fontenc}
\usepackage{babel}
\usepackage{graphicx}
%\usepackage{fancyhdr}
\usepackage[headheight=125pt, top = 160pt]{geometry}
\usepackage[dvipsnames]{xcolor}
\usepackage{mdframed}
\usepackage{fancybox}
\usepackage{adjustbox}
\usepackage{enumitem}
\usepackage{bbding}
\usepackage{tikz}
\usepackage{setspace}
\usepackage{csquotes}
\usepackage{sectsty}
\usepackage{tikz, blindtext}
\usepackage{float}
\usepackage{caption}
\usepackage{wrapfig}
\usepackage{listings}
\usepackage{lipsum}
\usepackage[usestackEOL]{stackengine}

\definecolor{myblue}{RGB}{100,127,255}

\usepackage[pagestyles]{titlesec}

\renewpagestyle{plain}{%
\headrule
\sethead{}{\Longstack{\includegraphics[width=\textwidth]{forestfloor.jpg} \\
\textcolor{myblue}{Whatever} \\ BLA BLA BLA}}{}
\setfoot{}{\thepage}{}
}

\pagestyle{plain}
\begin{document}

\chapter{One}

\lipsum[1-15]

\chapter{Two}

\lipsum[1-15]

\end{document}