Firefox Browser Crashes Without Crash Error
I have two issues that seem to be related. I have a Mac (Catalina 10.15.6) and I use the Firefox browser. I've adjusted my preferences and selected Google as my Default Search Engine. My issue is that when I "Quit" Firefox and open it again my Default Search Engine gets changed to the Browser Default (which seems to be Yahoo but isn't listed as that). I then have to go back to my preferences and change the setting. I've tried Removing all the Search Engines in the One-Click Search Engine list except for Google but when my settings get changed, the Browser Default search engine pops back up in that list. My related issue is that I'll be in the middle of doing things in the Firefox Browser when it will suddenly close. I don't get a warning nor a crash report. It's just suddenly closed as if I "Quit" my browser. When this happens, my Search Engine settings change as well.
To fix this issue I've tried changing settings, tried uninstalling/deleting the Firefox application and reinstalling it from the Firefox website using a different browser. None of these attempts fix these issues. I'm getting quite frustrated with this glitch. I'm a relatively new Mac user so am not as familiar with how to troubleshoot things as deeply as I do in the PC world. I didn't have these issues with Firefox on other OS's (Ubuntu & Windows). Is there a fix that doesn't involve me installing any other external apps?