When I open up Preferences in Firefox-ESR, I see the above message (in quotes). Why is that? Apparently I can’t change some of the preferences.
You should be able to change everything as usual, IIRC this message comes only because of the way
firefox-esr-mobile-tweaks is implemented.
Now I know what’s wrong:
OK button that has to be tapped. It’s totally invisible and inaccessible unless you shrink the screen down to tiny scale. I had thought that the settings just take effect immediately, but after checking Firefox-ESR on my computer, I realized the problem.