Fonts in new install on Zorin

[pkmon...@aim.com]

Long time Windows user trying to convert to Linux on Zorin on an older computer with 16 GB RAM and 2 TB new spinning Hdd.  Been having trouble getting note taker apps, like Cherry Tree, to change font style and size, which is critical to me, so, with the help of the Google AI I installed NotecasePro.  But still having difficulties.  Preset to Nimbus Roman at 14 points, I try to change just the size to 16 but then it loses the font style and changes to Sans.  Nothing I do, and I've tried numerous combinations, changes the style away from Sans. The size will change but nothing else.  I have tried to use the Style Manager but i frankly don't understand how it works.  I think I created a style but how do you get it to work in a note?

I'm wondering if I've downloaded the right setup file.  Zorin OS 18.1 Core  Was told that is Ubuntu 24.04 LTS system architecture so I downloaded and installed  Ubuntu 24.04 (amd64) deb.  Is that correct?