It sounds that for whatever reason Firefox is not saving your preferences. So I think you should take a look at Preferences are not saved, which has got alot of useful information about that specific problem. Specifically the Locked preferences file and the Corrupt preferences file sections. Let me know if that helps. If not, we'll try some more in depth steps.

Thank you for the quick reply. I tried all the steps and the settings still would not save and the appearance would still revert back to the basic theme without saving the previous persona. Any other ideas on what I should do?

Well, if that didn't work, I think the easiest way is to set up a new profile, transfer your personal data to the new profile, and use it for your daily use.

Read https://support.mozilla.org/en-US/kb/Managing-profiles, which explains how to create a new profile. Do not delete your old one.

After you have a new profile created, please read Recovering important data from an old profile, which explains how to move your personal information from your old profile to your new one. Only move over the information you need, as the less we have to move from the old corrupted one the better.

That worked. Thank you so much for the quick and thorough guide.