How do I get the screen to adjust to vertical and horizontal positioning?

[Selyasa]

When I'm holding the phone vertically and switch it to horizontal, it doesn't reposition. How do I make it change?

 

[belodion]

Welcome.

Make sure that Auto Rotate is on. That may be one of the quick settings options when you swipe down from the top of the screen, otherwise it will be in the main Settings.
If not working, try a Power Off and Restart. If no go, try Safe Mode.