Save data Problems

I keep running into these problems where it says his file is being edited by another user, even though Im only using this account so I cant save the file, and then when I try to finish my project at school with the pc I do alot of work to it, and I sign in with the same account but since its a different device they made me lose all that work before the do date. And if you go to safari however, all the data is there!So this app is just terrible

Bsuxbwgzuuwhqhuau about Microsoft PowerPoint, v1.25