if it was the desktop version, i would say "never look at help:about" as that invisibly triggers an update for no readily apparent reason.

on mobile, this is a novel issue to me. i always have to choose an update, even for ff nightly, with app store set against auto updates.

ok, on mobile, it may be the about:firefox page under Settings. if you look to check your version ... you are doomed.

where are update settings in the mobile browser? i don't even see them.

On my version of firefox mobile its in the settings option under customize, as i said i already have this set to never update but thrice now it has done so overnight while i sleep despite each night reconfirming that auto-updates are turned off on both the app and the playstore.

That setting must be gone in current versions. I vaguely recall "Customize" but cannot find it in a menu for any flavor of ff i have on my phone.

Long ago i had such behavior from various apps until i installed a firewall and blocked them from connecting to their update domains. I may have also disabled services but that would have been for really intransigent items like facebook products.

I hope someone else has an answer, as the only cause i had found for ff updating against my wishes has been looking at the version information page.

Good luck. I know how annoying this sort of thing can be. Unfortunately the IT ecosystem has decided that we neither own nor control our equipment and software.

If you want to try something more hacky, you can open about:config in the address bar and search "update". Edit values for update check interval, break the update domain (insert some nonexistent gibberish URL), and try edits with other settings if necessary.