title: Can't manage two get page numbers shown at the outside of a twosided PDF
body: <p>I am trying to change the page numbering from being at the footer's center, to a more book like page numbering where the numbers are always located at the outside of a page (odd page nubmer -> left sided, even page number -> right sided).</p>
  
  <p>I am not very familiar with Lyx, so I don't know which code parts of my Lyx file are relevant to attach here.</p>
  
  <p>I tried using fancy but this didn't solve the problem. Using the code below, the page numbers are always displayed at the right lower corner.</p>
  
  <p>My attempt to  fix it using fancy:</p>
  
  <pre class="lang-latex prettyprint-override"><code>\pagestyle{fancy}
  \fancyfoot{}
  \fancyfoot[LE,RO]{\thepage}
  </code></pre>
  
  <p>First 85 lines of my Lyx file:</p>
  
  <pre class="lang-latex prettyprint-override"><code>#LyX 2.3 created this file. For more info see http://www.lyx.org/
  \lyxformat 544
  \begin_document
  \begin_header
  \save_transient_properties true
  \origin unavailable
  \textclass book
  \options oneside
  \use_default_options true
  \begin_modules
  customHeadersFooters
  \end_modules
  \maintain_unincluded_children false
  \language ngerman
  \language_package default
  \inputencoding auto
  \fontencoding global
  \font_roman "default" "default"
  \font_sans "default" "default"
  \font_typewriter "default" "default"
  \font_math "auto" "auto"
  \font_default_family sfdefault
  \use_non_tex_fonts false
  \font_sc false
  \font_osf false
  \font_sf_scale 100 100
  \font_tt_scale 100 100
  \use_microtype false
  \use_dash_ligatures false
  \graphics default
  \default_output_format default
  \output_sync 0
  \bibtex_command default
  \index_command default
  \paperfontsize default
  \spacing single
  \use_hyperref false
  \papersize a4paper
  \use_geometry true
  \use_package amsmath 1
  \use_package amssymb 1
  \use_package cancel 1
  \use_package esint 1
  \use_package mathdots 1
  \use_package mathtools 1
  \use_package mhchem 1
  \use_package stackrel 1
  \use_package stmaryrd 1
  \use_package undertilde 1
  \cite_engine basic
  \cite_engine_type default
  \biblio_style plain
  \use_bibtopic false
  \use_indices false
  \paperorientation portrait
  \suppress_date false
  \justification true
  \use_refstyle 1
  \use_minted 0
  \index Index
  \shortcut idx
  \color #008000
  \end_index
  \leftmargin 3cm
  \topmargin 3cm
  \bottommargin 3cm
  \secnumdepth 5
  \tocdepth 5
  \paragraph_separation indent
  \paragraph_indentation default
  \is_math_indent 0
  \math_numbering_side default
  \quotes_style polish
  \dynamic_quotes 0
  \papercolumns 1
  \papersides 2
  \paperpagestyle fancy
  \tracking_changes false
  \output_changes false
  \html_math_output 0
  \html_css_as_file 0
  \html_be_strict false
  \end_header
  
  \begin_body
  </code></pre>
  
  <p>If any further code is needed, feel free to ask me! Thanks</p>