I use Windows myself; the preference is still global for me.

I think the setting should work on Linux for tabs and toolbar (not necessarily the menu bar, as it may be drawn by the system). I don't know if all increments are implemented. Could you test 1.5 to see whether that makes any difference for tabs/toolbars?

I see use use the Firefox version from the Ubuntu repositories. In that case some toolbars might be under control of the OS and can't be affected by Firefox similar to how the main menu bar works on Mac.

You would have to check the settings in Linux. Alternative you can switch to the Firefox version from the Mozilla server. That version should work as expected.

• https://www.mozilla.org/en-US/firefox/all/

Thanks for the quick replies. I All works as it should in Windows. However, neither the version form the Canonical repository nor the one downloaded from Mozilla responds with a global change. I'll check with Ubuntu support to see if they have any suggestions.