On some models, if the active video input is a digital signal (HDMI or MHL input), the buttons have
the following functions.
Button
1
Menu
2
Brightness
3
Next Active Input
22
Chapter 4 Operating the monitor
Function
Opens the OSD (On-Screen Display) main menu, select a menu
item from the OSD, or closes the OSD menu.
Opens the Brightness adjustment scale.
Switches the monitor's input source to the next active input.