Subsurface 4.9.3 Mac OS Mojave
So under the General tab in Preferences, there's a dropdown that lets you change the font. Only problem is, once you do that, all the data in other fields gets squished to the point where it's impossible to read -- and you can't change the font back either. Kind of stupid to raise this question here, but can't think of anywhere else to try.
Screencaps attached.