Where is the registry that governs the fonts on Today's screen?

[New Daddy]

Where is the registry that governs the fonts on Today's screen?

I've recently installed an app that behaves badly by changing the default fonts for the Today's screen for the worse.
(For one thing, nothing is bold now, whereas the date and certain items on Today were bold before.)
Since the app itself is very useful, I want to keep the new app but put back the Today's screen back to what it was.