… I simply want to change the tablature font style and size in a Finale document. I'd like it to be larger and bold …

Are you talking about the font style and size of the TAB Clef?

You can edit the clef in the Clef Designer:

Document menu > Document Options > Clefs > Clef Designer…

To edit a TAB clef, select the clef.

You will see that a TAB clef is a shape (not a font character).

Click the button {Edit…} to get to the Shape Designer.

Or do you mean the font style and size of the TAB fret numbers?

Document menu > Document Options > Fonts > Notation > Tablature > Set Font…

Perfect. I was talking about the fret numbers. I appreciate the help!