Due to compatibility issues with the Bluetooth protocol version of the terminal device system, individual mobile phone or computer models may not support the volume adjustment protocol. This problem may occur with any TWS Bluetooth Earbuds available on the market. If you encounter this issue, you can try connecting the Earbuds to other commonly used devices to adjust the volume. If there is no abnormality, it can be confirmed that the problem lies with the terminal device rather than the Earbuds, so you can use the Earbuds with confidence.