re: Shower door bumping in top corner. How to level?

The glass is slipping out of the hinge. Its very common especially with a glass this large. Like others have said shim the bottom so the glass doesn't move, then you'll need to loosen the hinge plate to get it back in place. You need 2 people for sure. I would personally call whoever installed it before I did that myself.

I've worked in a glass shop for 20 years just not as an installer.