Follow these steps to troubleshoot the issue:
- Install the Sony | Headphones Connect app, then change the volume using the app.
Note: On a device that can be linked with the earbud headphones, you can change the volume level of the headphones using that device. You won't be able to change the headphones volume on a device that can't be linked with the headphones
- Adjust the volume on the connected Bluetooth® device.
If the issue still occurs after following these steps, delete the pairing information for the headphones from the Bluetooth device, and pair them again.