I think being able to set a standard text style setting is an essential requirement. Without this, I have to change text type and size for every new note I create.
Right now, even updating the "Normal text" settings from customized text doesn't work across notes.
A tab in settings where one could set the defaults for all the text styles (Large Header, Medium Header, Small Header, and Normal Text) would work. For each new note, you'd start with these defaults and then could adjust if necessary.
It's not just about font size. I prefer Serif fonts to San Serif. In an application where I write so much and spend so much of my time, looking at a Sans Serif font is a constant annoyance.
And also, the font size problem shows up when I work on a device with high resolution. I don't want to have to scale up everything in my system settings--that creates an entirely new mess. Being able to change the default font size I write in, as I can do in other programs, would fix this.