How to adjust the volume when using Q8 music sharing

After the main device is connected to the mobile phone, the music is shared. The volume of the main device is synchronized with the mobile phone, and the sub-device is the default volume of the machine.
Sub-device adjusts the volume: If the current state is intercom, click Volume +/- to control the intercom volume. If the current state is music, click Volume +/- to control the music volume.