The usual way to adjust menu fonts in TB, via Theme Font & Size Changer (fixed) probably won't work (yet) in TB 63beta until some updates are made to it (see the first CHANGED item here. In the meantime, you can look at various css files discussed here to achieve the same result. That approach may also work the same in Firefox until the TF&SC add-on is updated.

I tried the userCrome.css route however had no success with it. Perhaps I created the Chrome folder in the wrong location or didn’t do something else to point TB to it. I’m open to all suggestions. Thank you.

The userChrome.css file has to be in the chrome subfolder of the profile folder. See this post and this post for examples.

Thank you very, very, much. My problem was that I didn't have the Chrome folder in the correct location. I couldn't find the Profile folder. After searching a bit, I finally located it, moved my userChrome.css folder into it, and presto - success.