HP XP8010, XP8020 Reference Guide

To change the source, To hide or show the display

Reference Guide
To change the source
Press the source button on the projector or remote control, or
Open the on-screen menu, select input, and select the port to which the input 
source is connected. 
To hide or show the display
You can easily hide the display from your audience temporarily. 
Press the hide button on the remote control. The screen remains blank until you 
press the hide button again.
If you are using Microsoft
PowerPoint, you can also press the B key or the W key to 
hide the display. The screen remains blank until you press the B key or the W key