HP Pavilion 13-a010dx x360 Convertible PC - Manual (Page 16)

Component Description
NOTE: Be sure that the device cable has a 4-conductor
connector that supports both audio-out (headphone) and
audio-in (microphone).
(5) Volume button Controls speaker volume.
To decrease speaker volume, press the – edge of the
button.
To increase speaker volume, press the + edge of the
button.
8 Chapter 2 Getting to know your computer