Paragraphs and Page Breaks in Online Word keep breaking and displacing up or down after I save my do

This is probably a long shot, but I’ve been losing my mind trying to figure out how to fix this. 
I have to use Online Word for several courses I’m taking, and whenever I’m writing a paper in it, I usually have no issues in it. However, when I come back to a previously saved document, I notice that most of my paragraphs have been displaced either up or down, or page breaks that I’ve put in have completely broken. This has actually caused me to lose points on a paper or two, and I had to explain to my instructor that this is a problem I’ve been having for awhile. I have no idea how to fix this, and I’m trying to provide my instructors with a flawless paper that doesn’t have any formatting issues. If anyone can help out, I’d appreciate it. 

Thanks