hi,
when using a camera for 2nd display monitor, how can it be set to be full screen instead of left aligned of the screen? here is the current render result
This is not default behavior, so I would guess that the UV coordinates on the camera have changed. If you select the camera, its Camera component should have a field called Viewport Rect. Make sure that is set to X = 0, Y = 0, W = 1, H = 1.