I don't know whether this applies to your oldish version of FF. https://support.mozilla.org/en-US/kb/customize-new-tab-page

Thanks for responding! Not quite sure how I did it, but your response probably covers it. I ran some new updates and I'm guessing one of them got it. I appreciate your time.

Firefox is a web browser and not a Homepage or a web site or search engine.

It sounds like Firefox is working fine, just that it may be opening the default Homepage set in your third-party Mint provided Firefox web browser. https://support.mozilla.org/en-US/kb/how-to-set-the-home-page

Firefox from Mozilla has it's own internal software updates and default settings, however Mint provide their own package updates and settings for their Firefox builds. https://blog.linuxmint.com/?p=4259