Thanks for using Notezilla and your query.
On the sticky notes where you change to larger font size, can you check which editor your are using? Notezilla supports standard editor and markdown editor.
You can right click inside the sticky note and check if you get an option to "Switch to markdown editor" or "Switch to "standard editor".
Standard editor supports different font size but the phone doesn't support. So you will see the font size getting reset.
But markdown editor is supported on both Windows and phone app. Markdown as such doesn't support different font size. But you can use different Headings to use text of different sizes. H1, H2, H3 etc...
Below is the screenshot to guide you. Once you use headings, they will show has large text on phone app too. And they will not get reset on syncing.
