How do I stop Facebook from lowering quality?

The Facebook mobile app essentially allows a user to upload in low quality and what they call ‘HD’, with the default setting being low quality. To change that all that’s needed is to go into the main FB mobile Menu > Settings > Account Settings > Videos and Photos, then toggle the two sliders over to the right.

I see… Sometimes settings won’t work

That is right. What you find on Google is not updated always. Facebook always change their settings.