Inkscape is quite customizable. The easiest way to make customizations is through the Inkscape Preferences dialog. More extensive customizations can be made by modifying files in or adding files to the Inkscape preferences directories. The directory for changes shared by all users is
share/inkscape. The directory for personal changes is
~/.config/inkscape/ on Linux or
%userprofile%\Application Data\Inkscape\ on Windows.
Inkscape is most easily customizable through the Inkscape Preferences dialog (File → Inkscape Preferences... (Shift+Ctrl+P)).
There are too many ...