Dell P2418HZM 23.8" 16:9 IPS Monitor - Manual (Page 61)

Operating your monitor |
61
If only the HDMI or DP cable is connected from your monitor to the computer, only
one speaker named
DELL P2418HZ from the monitor will show in the Sound setting
interface.
click DELL P2418HZ , and then click Set Default , the monitor speaker will be used as
the default setting.