Editing baroque lute tablature?

How do you modify the fingering symbols associated with notes in baroque lute tablature?

I have a piece in C Major, meaning the open 7th string should denote a G natural. However, when I place a G note, it renders it as "/b", as though the string were tuned in G flat. I have to set the note to G# to get the fingering to render correctly as "a".

How do I fix this? I don't see any editing options under staff properties.