I have trouble accessing the bottom half/top half of the screen on the P10

Use the Gaze Analyzer to determine how the camera is picking up your eyes. This information may help for re-positioning/re-calibrating. There are three main tricks you can try:

1. Change the calibration area on the screen and re-calibrate. The computer then will take a mirror image of that calibration for use with the other half of the screen.
2. If the user has bifocals/trifocals, it may be helpful to angle the P10 slightly greater than the recommended 90 degrees from the eyes.
3. Put the most important buttons in the most accessible area of the screen and larger buttons in the more difficult area of the screen.