After the Earbuds are connected to a mobile phone, you can either adjust the volume directly on the mobile phone device or enable the double-tap and hold function of the Earbuds on the control settings page of the Nothing X App.
A 1-second tap and hold will adjust the volume (when this operation is triggered and the hold state is maintained, the volume will increase or decrease by one level every 0.9 seconds, and the volume adjustment will stop when the button is released).