Answer by egreg for ClassicThesis: override options of a previously loaded classicthesis package

André Miede's idea is that one should copy classicthesis-preamble.sty in the working directory and changes is to suit the needs for a particular job.

Not a very good idea, in my opinion, as the code in this package is quite intimidating for the novice and does not limit itself to some

\usepackage[<options>]{<package>}

lines, maybe with some auxiliary definitions. It's not very clear why saying

\PassOptionsToPackage{fleqn}{amsmath}           % math environments and more by the AMS  \RequirePackage{amsmath}

is to be preferred to the simpler

\usepackage[fleqn]{amsmath}

or what the novice user is supposed to do with

\ifthenelse{\boolean{cld@backref}}%{%                \PassOptionsToPackage{hyperpageref}{backref}                \RequirePackage{backref} % to be loaded after hyperref package                    \renewcommand{\backreftwosep}{ and~} % seperate 2 pages                   \renewcommand{\backreflastsep}{, and~} % seperate last of longer list                   \renewcommand*{\backref}[1]{}  % Disable standard                   \renewcommand*{\backrefalt}[4]{% Detailed backref                      \ifcase #1 %                         \backrefnotcitedstring%                      \or%                         \backrefcitedsinglestring{#2}%                      \else%                         \backrefcitedmultistring{#2}%                      \fi}%}{\relax}

which is code that should go in classicthesis.sty.

If you feel intimidated by classicthesis-preamble.sty, then don't load it and add the packages you need, passing the desired options directly to classicthesis.

For example

\documentclass[...]{scrbook}\usepackage[fleqn]{amsmath}\usepackage[eulerchapternumbers,subfig,beramono,eulermath,parts]{classicthesis}\usepackage{hyperref}\hypersetup{%draft, % = no hyperlinking at all (useful in b/w printouts)    colorlinks=true, linktocpage=true, pdfstartpage=3, pdfstartview=FitV,%    % uncomment the following line if you want to have black links (e.g., for printing)    %colorlinks=false, linktocpage=false, pdfborder={0 0 0}, pdfstartpage=3, pdfstartview=FitV,%     breaklinks=true, pdfpagemode=UseNone, pageanchor=true, pdfpagemode=UseOutlines,%    plainpages=false, bookmarksnumbered, bookmarksopen=true, bookmarksopenlevel=1,%    hypertexnames=true, pdfhighlight=/O,%hyperfootnotes=true,%nesting=true,%frenchlinks,%    urlcolor=webbrown, linkcolor=RoyalBlue, citecolor=webgreen, %pagecolor=RoyalBlue,%    %urlcolor=Black, linkcolor=Black, citecolor=Black, %pagecolor=Black,%    pdftitle={},%    pdfauthor={},%    pdfsubject={},%    pdfkeywords={},%    pdfcreator={pdfLaTeX},%    pdfproducer={LaTeX with hyperref and classicthesis}%}   

which might be sufficient for many purposes.