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

In a Private Message, EOC said;

Thank you for your assistance. I followed the instructions. Yours and the sequence outlined in the link you provided. Unfortunately, I couldn't find the "Eject" prompt on the menu that popped up (i.e., after sliding the Firefox Logo over the Application File Folder... and employing the "Control Click" move).

But I'm an old guy so maybe I did something wrong. On the "Desk Top" [if that is what iMac calls it (?)], I noticed several Data-Disk Icons with Firefox Logo, which when 'right-clicked' did present the "Eject" option. I did that. So we'll see what happens.

What I don't understand is the 'rigmarole'... that is why cant we log onto Firefox, identify ourselves (it recognized me and sent code to my email) and then with that just have it work as it does on my Dell Laptop?

Ah well, we'll see what happens. I do appreciate your attempt to help. Maybe it will intuitively come around.

Stay Safe!

Vic L.

I called for more help.