CubeMenu provides ability for managing FreeCAD navigation cube menu structure and overall appearance.
CubeMenu is a FreeCAD module and can be installed with the FreeCAD Addon Manager.
Install path for FreeCAD modules depends on the operating system used.
Linux:
/home/user/.FreeCAD/Mod/CubeMenu/InitGui.py
macOS:
/Users/user_name/Library/Preferences/FreeCAD/Mod/CubeMenu/InitGui.py
Windows:
C:\Users\user_name\AppData\Roaming\FreeCAD\Mod\CubeMenu\InitGui.py
FreeCAD forum thread: https://forum.freecadweb.org/viewtopic.php?f=34&t=43338