If your Firefox is the one managed by your distro, it may be customized to hide the section of the Preferences page where you can have Firefox notify you when an update is available rather than installing it immediately. Or it may be visible on the page but overridden.

In that case, you could consider using the generic Linux build rather than the one from your package manager.

https://www.mozilla.org/firefox/all/#product-desktop-release

Or check your distro's forums for advice.

Thank you I will install the one suggested. I fed with these repetitive interruptions of upgrades..