This can be due to one of 3 possibilities. The first possibility is that there is a physical defect like a dimple, divot, or crease in the LCD touch screen that is causing the touch screen to register that defect as a button press instead of your actual button presses. The second possibility is that the glass inside the touch screen is cracked or broken. This can cause many errors in the touch screen and your problem is one of those possible errors. The final possibility is that the motherboard deep inside the camera is damaged in some way. the good news here is that to have your exact problem the motherboard would have to be damaged in certain ways. To damage the motherboard in those ways only and not show other problems in your camera is unlikely, so the cause of your problem is likely one of the other 2 problems. The first 2 problems would require replacing the LCD touch screen itself. If the motherboard is the problem, then replacing the motherboard is your best bet. Given that motherboards are a kind of electronic circuit board which can be expensive, I would compare the cost of a new motherboard with the cost of a new camera before ordering a replacement. You can find more information using the troubleshooting guide.