Acer XF251Q User Manual page 23

Adjusting the Volume
Open the Volume control and set the volume using the arrows. When you are
done, use to go back one level.
Note: Adjustment of the volume control as well as the equalizer to
other settings than the center position may increase the ear/
headphone output voltage and therefore the sound pressure level.
Selecting the Input
Open the input control and select HDMI or VGA. When you are done, use
to go back one level.
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