Yamaha YDP-123 Owner's Manual page 22

Adjusting the volume
You can change the volume of the metronome sound.
While holding down the button, press one of the C1–G2 keys
[METRONOME]
to determine the volume.
METRONOME
The lowest key
C1 G2
The volume level increases as you press higher keys.
2.
Stop the metronome.
Turn off the metronome by pressing the button.
[METRONOME]
22 Selecting & Playing Voices
YDP-123