Iiyama ProLite LE7540UHS User Manual page 21

 Adjust the volume of sound
Press the + / - button on the display or the remote control
to adjust the volume of sound when the menu page is not
displayed on the screen.
[Display]
 Switch the input signal
This is activated when you successively press the INPUT
button on the display or the SOURCE button on the remote
control.
[Display]
[Remote Control]
[Remote Control]
BEFORE YOU OPERATE THE DISPLAY 17