Hi Mark,
Welcome to the forums.
I haven't played around with the fonts too much. What I did was to go to
Opt | Preferences and then click on "Notation". I then clicked on the button called "Jazz Fonts", as highlighted below.

Clicking on the above button set everything as shown in the image. (Please note that I changed the font sizes to 80% for all fonts.)
After doing the above, when I typed a lowercase "b" in the title box, it gave me exactly that. It looked suitable to use as a flat sign.
Hope this helps,
Noel