Adjustment Issues With Viewsonic A90f+

I have had a Viewsonic A90f+ as my monitor for about 7 years, and a couple of years ago, it started having issues with the adjustments. Whenever the monitor is turned on, the adjustment for horizontal/vertical size/position and pincushion change, and the picture is cut off or too small. None of the adjustments I make stay after the monitor is turned off, and the auto adjust makes the picture too small, with black bars on all sides. Does anyone have any idea what's wrong with it?

Have you changed your computer or graphics card?