My biggest complaint with Firefox is the upgrade nag. I get it, I need to upgrade, why can't they just put a reminder in the corner instead of insisting I click a dismiss button every hour.
I am cognizant it may not be universally true, but often those updates come with CVEs attached to them, a bad side effect of exposing several JITed virtual machines to the wild Internet. I know such advice from random folks depends heavily upon ones threat model, but bear the security consequences in mind, and that goes double if it wouldn't just be your network that may get taken over in an incident
As a heads up though as suggested by the name "ManualAppUpdateOnly" doesn't just disable the notification it completely disables the entire auto-update system. Not only will you not get notifications about updates you will not get updates at all until you remember to check the about dialog or manually download them. This is intended for environments that have managed packages where the browser doesn't need to update itself.
> Not only will you not get notifications about updates you will not get updates at all until you remember to check the about dialog or manually download them.
What if you feel like you can handle this not particularly difficult problem?
Then activate the setting and enjoy. If what you actually want is silent manual updates not just for the update notifications to go away then it's the perfect option for you.
If you are using Nightly (which updates twice a day), you can turn on "Show fewer update notification prompts" in your settings (about:preferences#general) which removes the update nag and puts a small reminder in the top right corner like you asked.
