If the projected image is not evenly rectangular,
try the following solutions: 
- 
Place the
projector directly in front of the center of the screen, facing it
squarely, if possible.
- 
If you
adjusted the projector height using the projector feet, press the
keystone buttons on the projector to adjust the image shape.
- 
Turn on
automatic keystone adjustments using the projector's menus.
- 
Adjust the
position of the projector's horizontal keystone slider.
- 
Adjust the
Quick Corner setting to correct the
image shape.