Open the menu with the "OSD" button on the side of the monitor, and then find the "VOLUME" in "SIGNAL SOURCE". Please note that after setting the volume, you need to press the "OSD" button to save the settings.

Hotkey: The "-" on the side of the monitor.

Note: If you need to play audio using the monitor's speakers, please make sure that ARZOPA is set as the audio output device on your connected device.