OK, I assume that I should restart or at least log out and back in when I change system settings.

Usually I'm following instructions that I found online and they tell you what to do there. I definitely don't go into Group Policy and edit things all willy-nilly.

This seems to be the case on many OSes. I was documenting my workstation setup recently and I'll share one entry here:

    ### Firefox opening to manjaro.org instead of new-tab

    - Look for settings in Firefox to disable this. No findeee!
    - Search the net to discover others talking about this. Many say just 
    uninstall `manjaro-browser-settings`.
    - Remove `manjaro-browser-settings`.
      - Failure: Firefox still behaves the same.
    - Decide to uninstall Firefox and reinstall it. However, I will install 
    Chrome first.
    - Use _Add/Remove Software_ app preferences to enable AUR repository, 
    then refresh databases.
    - Install Chrome from AUR. It works.
    - Uninstall Firefox and reinstall it.
      - Success: Firefox no longer opens to manjaro.org.
      - (There might have been a reboot somewhere in there - it doesn't 
    hurt to sprinkle them in randomly when
    practicing voodoo computing!)

Also it seems like with this OS, if I don't reboot after an update or changing certain settings - things start breaking.

Maybe one day, we'll have the perfect OS! But as far as I know it doesn't exist yet. :)