Have you checked Keystone?
The screen is not level and you can fix this by adjusting Keystone.
How to fix
Menu → Settings → Option → Auto Keystone : On or Keystone
If it has Auto Keystone feature, turn it On.
It if doesn’t have, select Keystone and adjust manually.
※ What is Keystone?
Keystone is a function that allows multimedia projectors that are not placed perpendicular to the horizontal centerline of the screen to skew the output image, thereby making it rectangular.
The higher the value you set for the Keystone, the lower the quality of the image may be. So you are suggested to move it up/down/left/right physically to place it perpendicular to the screen as much as possible, then use the Keystone function.
Mini Beam provides Keystone function for Up/Down, but not Left/Right,
For Left/Right adjustment, move the Mini Beam physically.
If you install it on the ceiling, select ‘reverse’.(Option->PJT Mode->Reverse)