Discrepancies exist

I am trying to modify menus in LibreOffice Writer. I am using
‘LibreOffice_7.0.4_Linux_x86-64_deb’ on Ubuntu 20.04. I have visited
https://documentation.libreoffice.org/assets/Uploads/Documentation/en/GS5.2/HTML/GS5214-CustomizingLibreOffice.html
<https://documentation.libreoffice.org/assets/Uploads/Documentation/en/GS5.2/HTML/GS5214-CustomizingLibreOffice.html>’
and on the page I see information about creating a New menu. Reference
is made to a New button that is present in the Customize dialog.
However, my Customize dialog has no such button. I have tried different
office applications and none of them produce a Customize dialog with a
New menu button. Can you explain why this is? Thanks for your time.

You are reading the guide for version 5.2. Please refer to the guide for 7.0, page 410: https://documentation.libreoffice.org/assets/Uploads/Documentation/en/GS7.0/GS70-GettingStarted.pdf

Ilmari