OK, if you purchased a projector without understanding this issue in advance, you are WAY outside your understanding of the requirements of projecting images. First... to get the best image quality, NEVER use the Keystone controls in the projector. Instead, you MUST align the projector properly. The middle of the projector lens must be placed at the same height as the top of the projection screen. The center of the lens on the projector must be aimed at the CENTER of the projection screed (center of the top edge of the projection screen). AND, the distance from the left edge of the screen to the center of the projection lens MUST be the SAME as the distance from the center of the projector's lens to the RIGHT edge of the projection screen. Then you must adjust the distance of the projector from the projection screen so that the edges of the image are the same size as the edges of the projection screen. This is done by moving the projector or screen closer or farther until the image fills the projection screen. "Nicer" projectors may have a Zoom Lens that allows you to control the size of the image without having to move the projector. Then you use the vertical alignment adjustment (manual on less expensive projectors, motorized and remote controllable in more expensive projectors) to get the top and bottom of the projected image to match the top and bottom edges of the projection screen. This is VERY VERY BASIC knowledge about using a projector. I would suggest you search for information about projector installation and setup so you are not missing important concepts. There are many things to understand about geometry and optics when it comes to setting-up a projector. ALSO, some projectors have settings for where the projector is mounted: in front of the screen on a low table, in front of the screen on a tall rack with the projector right-side-up, in front of the screen in a Ceiling Mount bracket that turns the projector upside down, other settings change the image so it is correct when the projector is BEHIND the projection screen using a rear-projection screen with the projector right side up or upside-down. SOME of this is CERTAINLY in the manual you have for the ViewSonic projector. But there is much more on web sites that have information about using projectors. Honestly, your question is so simple, it would be similar to buying an automobile but not knowing how to operate the vehicle in reverse, or not knowing the steering wheel can turn the car right or left. Really. When you want to use some technology (like a projector) and you do not understand the basic things about the technology, you may never use the technology properly. So it is time to become an expert on installing and using a projector. There is enough information about projection online for you to be able to make yourself an expert.
