Whenever I check "about Firefox" under the Help menu . . . .

When you do this, the browser will check for updates whatever your settings are. If you want to check what version you have: Type about:support<enter> in the address bar.

If you want to check the current version of Firefox: https://www.mozilla.org/en-US/firefox/releasenotes/

Fred, this does not address the issue. I understand that FF always checks for updates when I choose "About Firefox". My point was that Firefox autonomously changes my choice BACK to "Automatically install updates (recommended)" whenever an update is installed. I DON'T WANT FF TO MAKE THAT CHANGE!

https://support.mozilla.org/en-US/kb/how-to-fix-preferences-wont-save

Note: Some software, like Advanced SystemCare with Surfing Protection, can protect files in the Firefox profile folder against changes. If you have such software then check the settings or uninstall this software.

Macs: Make sure you install Firefox properly and that you do not run Firefox from within the DMG (Disk Images) file. https://support.mozilla.org/en-US/kb/how-download-and-install-firefox-mac

You can set Windows to show hidden files and folders: https://support.microsoft.com/en-us/windows/show-hidden-files-0320fe58-0117-fd59-6851-9b7f9840fdb2

Your upgrade preference is stored here:

C:\ProgramData\Mozilla\updates

Each different kind of Firefox that has been installed will have a separate folder here, so there might only be one or there might be more than one (for example, 32-bit vs. 64-bit, regular release vs. ESR). Each folder should have an update-config.json file and if you set Firefox to ask your before installing, its contents should look like this:

{"__DEFAULTS__":{"app.update.auto":true,"app.update.background.enabled":false},"app.update.auto":false}

Is that file/folder getting cleared when you update?

Thanks for your response, jscher2000.

The file currently contains the string that you listed. I won't know if that file gets cleared until my next update. If it is, how would I prevent that from happening?

The file shouldn't get cleared by a normal update. Some companies use third party software to manage updating, and that might flush out old files to prevent possibly mixed files, but I don't think that is common on a home computer.

jscher2000,

Assuming that the folder contents is changed when I update, would it help if I just write-protect that folder?

As long as that JSON file is in place when Firefox checks for updates, it should honor your instructions. It's worth rechecking after update to make sure it's still there, but the folder is used to stage the update, so I think write-protecting it will lead to an error.