FreeCAD has a powerful Preferences page and is really customizable. But when switching between different project types (e.g. working on a building and switching to a part object later on) you have to set the preferences (unit settings, draft grid, sketcher,...) back and forth to have to perfect environment for your task.
This happened to me in the past quite often. Don't know if others have the problem too. Googled around and searched the forum but could not find a solution for my problem. Maybe I used the wrong search terms or it simply does not exist
So i created a small Macro that can help to overcome this issue. https://github.com/furti/FreeCAD-PreferencesPresets
Maybe this can be of use for others too.
Basically the macro copies the "user.cfg" and "system.cfg" in your FreeCAD AppDataDir to another Location and creates a executable script file for you, that starts FreeCAD with the "--user-cfg" and "--system-cfg" flags. So you can have multiple executables that preload FreeCAD with the preferences you need for your current project type.