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I'm currently typing my dissertation. The requirement for text margin is top 2cm, right 2cm, left 4cm and bottom 2cm. My setting works for all pages, except the pages at which the chapter titles are located. Is there anyway to solve it? I'm using pdfLaTeX compiler.

documentclass[12pt,a4paper]{report}

%%%%%%%%Package
usepackage{amsmath, amsthm, amssymb}
usepackage{array}

usepackage{anysize}
usepackage{faktor}
usepackage{placeins}
usepackage{float}

usepackage{enumerate}
usepackage{fancyhdr}%for page number font
usepackage{lmodern}%also for page number font
usepackage[pdftex]{graphicx}
usepackage{caption}

usepackage{booktabs, calc, cleveref}

usepackage{mathptmx}%Font: Times New Roman

%usepackage{fontspec}
usepackage{setspace}
usepackage[font={small},labelfont=bf]{caption}
usepackage[titles]{tocloft}%needed for preamble, specifically cftsetindents
usepackage[notquote]{hanging}%for hanging indentation, used in the List of Publications section, [notquote] required so file doesn't crash
usepackage{sectsty}%used to format chapter title to be centre etc.
chapternumberfont{nohangcenteringlargeMakeUppercase} %to format the font for the 'Chapter' number
chaptertitlefont{nohangcenteringlargeMakeUppercase}
sectionfont{fontsize{12}{15}selectfont}

usepackage{tikz}
usepackage[final]{pdfpages}%to insert the Original Literary Work Declaration from a PDF file

%setmainfont{Times New Roman} %Font: Times New Roman

usepackage[footskip=1cm]{geometry}%Set Margin
geometry{
left=40mm,
right=20mm,
top=20mm,
bottom=20mm,
}

%%%%%%%

renewcommand{cftchapleader}{cftdotfill{cftdotsep}} % for chapters dots
renewcommandcftchappresnum{CHAPTER } % prefix "Chapter " to chapter number in ToC
cftsetindents{chapter}{0em}{6em} % set amount of indenting

pagestyle{fancy}
lhead{}
chead{}
rhead{}
lfoot{}
cfoot{}
rfoot{thepage}
renewcommand{headrulewidth}{0pt}
renewcommand{footrulewidth}{0pt}

%%%%
fancypagestyle{plain}{
fancyfoot{}
fancyfoot[R]{fontsize{10pt}{10pt}selectfontthepage}
renewcommand{headrulewidth}{0pt}
renewcommand{footrulewidth}{0pt}}
pagestyle{plain}

%%%%

renewcommand{contentsname}{Table of Contents}%Change 'Contents' to 'Table of Contents'
renewcommand{bibname}{REFERENCES}%Used to change the name "Bibliography" to "References"

%%%%%
newtheorem{pro}{Proposition}[section]
newtheorem{thm}{Theorem}[section]
newtheorem{cor}{Corollary}[section]
newtheorem{rem}{Remark}[section]
newtheorem{exm}{Example}[section]
newtheorem{lem}{Lemma}[section]
newtheorem{defin}{Definition}[section]
newtheorem{ques}{Question}[section]
newtheorem{conj}{Conjecture}[section]

setstretch{2}

%%%%%%%%%%%
%%%%%%%%%%%%
begin{document}

pagenumbering{arabic}
setcounter{page}{1}

%Chapter 1
chapter{MakeUppercase{INTRODUCTION}}

%Background of study
section{Background of study}
Associating a group with a graph and finding relationships between them is an area of research that has generated much interest. Research on this subject aims at investigating relationships between groups and graphs and at exploring applications of one to the other.

newpage
The main contributions of this work

end{document}