[Update: A temporary fix has been found! If you have any idea how the weirdness started in the first place though, please share.]

Help me! Please! I'm trying to create a poster on powerpoint, and it won't keep saved changes.

So I'll have the document, it will be what I've just done, and then it just automatically goes back to what it used to be SEVERAL SAVES AGO. It happens when I scroll a bit, it happens when it just sits there. I have no idea what the fuck is going on, google isn't helping, does anyone know what's happening and how I can stop it?