The first thing that comes to mind is graphics card. It is just a shot in the dark, though. It is possible that SW 2018 has different graphics card driver requirements than SW 2017, so you may need to go here to check out whether or not you are running the latest approved and tested driver.
Check if perspective view is on? If yes then turn that off.
Check if you have any arc center point away in space.
I haven't had any problems with the auto-rotate when creating new sketches, but often when editing a sketch it will zoom in on the origin instead of encompassing the whole sketch. I think I remember someone from SW here being aware of the issue, but I'm not sure.