Microtek C783 User Manual page 9

Use the power switch to turn power ON or OFF. We recommend
turning your system power on first, followed by the LCD monitor.
These keys have two functions, controlled by the MENU key. When
the OSD screen is activated, these two keys are uses to decrease or
increase the values of the selected items. When the OSD screen is
NOT activated, these two keys are used to turn up or turn down
volume.
These keys have two functions, controlled by the MENU key. When
the OSD screen is activated, these two keys are used to move the
cursor up or down to select item. When the OSD screen is NOT
activated, these two keys are used to change the Brightness value.
Press the Menu key to activate the on-screen display screen. The
Menu key is a toggle key; press twice to either turn the on-screen
display ON or OFF. After 30 seconds of idle time, the OSD screen will
automatically turn off.
Press this key to get better visual performance.