1.There is a memory function within the BTR3K so that it can automatically adjust the volume. 2. We have deliberately designed the volume adjustment of the BTR3K out of sync with the mobile phone which makes it possible to adjust the volume in a more precise level and avoid many problems. What the mobile phone can adjust is the the volume of the Bluetooth codec. If its volume is too small, the dynamic effect would be affected. While the BTR3K controls the volume of decoding and amplification which can decrease the loss of the sound quality. Therefore, it is recommended to adjust the volume of the phone to the maximum, and control the volume by the BTR3K.