How do I edit notes? Like, change the writing and deleting some.

Click on the note and then the white text box, there you can delete/modify the notes.

To add a new note click the add note on the left menu bar.

I transferred the translation from this danbooru.donmai.us/post/show/899039/ to this safebooru.org/index.php?page=post&s=view&id=603825 but the note boxes themselves reset their size every time I refresh, it's kind of irritating. Problem, or am I derping and forgetting to hit a button or something

Holy cow that last image is a mess.

Okay what you do is you move and resize the note where you want it to be, then click on the text and then the save button. Then the note box will stay resized.

Thanks for translating :)