page number in top right intersects with the page text

Question

My text and the top right page number seem to intersect when using fancyhdr:

\documentclass[a4paper,oneside,12pt]{report}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{bm}
\usepackage{graphicx}
\linespread{1.5}
\usepackage{subfigure}
\usepackage{float}
\usepackage{url}
\setcounter{secnumdepth}{5}
\usepackage{hyperref}
\usepackage [numbers,square,sort]{natbib}
\usepackage{ulem}
\usepackage[cm]{fullpage}
\addtolength{\voffset}{1.0cm}
\usepackage{pslatex}  % for times new roman font
\usepackage[nonumberlist]{glossaries}
\usepackage[top=2cm, bottom=2.5cm, left=3.5cm, right=2.5cm]{geometry}
\usepackage{fancyhdr}

%\addtolength{\textheight}{3.5cm}


\hypersetup{
colorlinks,
citecolor=black,
filecolor=black,
linkcolor=black,
urlcolor=black
}


\makeglossaries
\newcommand{\HRule}{\rule{\linewidth}{0.5mm}}
\newcommand{\abs}[1]{ \lvert #1 \rvert}


\pagenumbering{roman}

\input{./glossary.glo}

\begin{document}
\pagestyle{myheadings}


\input{./chapters/titlepage.tex}
\input{./chapters/declaration.tex}
\input{./chapters/dedication.tex}
\input{./chapters/abstract.tex}
\tableofcontents
\listoftables
\listoffigures
\include{./chapters/acknowledgement.tex}
\pagenumbering{arabic}
\include{./chapters/introduction}
\include{./chapters/theory}
\include{./chapters/literature}
\include{./chapters/methodology}
\include{./chapters/results}
\include{./chapters/discussion}
\include{./chapters/conclusion}

\printglossaries
\begin{small}
\bibliographystyle{ieeetr}

\bibliography{projbib}
\end{small}
\end{document}

Answer 1

A minimal working example of your problem is

\documentclass[a4paper,oneside,12pt]{report}
\usepackage[cm]{fullpage}
\usepackage{fancyhdr}
\usepackage{lipsum}

\begin{document}
\pagestyle{myheadings}

\pagenumbering{arabic}
\lipsum[1]

\end{document}

It is resolved by replacing the \usepackage[cm]{fullpage} by your geometry package line

\usepackage[top=2cm, bottom=2.5cm, left=3.5cm, right=2.5cm]{geometry}

Thus in your original file you should just delete the line with the fullpage package.

In general the geometry package is to be preferred over the older fullpage exactly because of this type of problem.