What kind of mobile device are you playing on? The orientation shouldn't have changed between v4 and v5, so I'm a bit confused as to what might be happening. (Phones are still using portrait mode, while tablets will approximate landscape. The aspect ratios have changed, but not the basic layout.)
Also, I read that some people with the newer Android devices can barely get Ren'Py games to run after the 7.4.0 update. The developer of Ren'Py is working on a fix for 7.4.3, but since 7.4.2 just came out it's going to be at least a week or so before the hotfix comes out. Sounds like I may need to come up with a way to re-package v5 when that patch comes out... (I've already started implementing changes for v6, but if the game isn't playable then I should try to put a playable version out, one way or another.)