check out that atom flight manual, you need to read and uncheck the open welcome windows on start check boxes (have a read through those pesky windows before closing them). I think that line has to do with the text wrap. To get the text to wrap, turn on soft wrap in the settings menu.
@Kevin has a great point about not getting too attached to one editor or theme. Things change fast. Atom is maybe the 5th 10th? editor I’ve used in my career and likely if you ever collaborate in the future, you’re collaborator will have a completely different setup than you will so its good to get used to looking at all sorts of editors & syntax themes.