These are the very potential problems I have been afraid of. I downloaded the plugin and activated it, but having been a chicken, I have not used it. I am also new and would not want to mess up my theme or be stuck with a font I don't like. Here are a couple questions in addition to the above.
Sorry, if I am asking questions that make you "sigh." Descriptions and instruction are not clear to me, a newbie, at all what this plugin does . . .
1. Once you change a font on one page, would it change all pages? Even if it is the header of a post (content, not the header of the page)?
2. How can I make sure I can change it back to the original font?
If it is too confusing, I will start a new thread. So Ignore me or tell me so.