If the volume is very low from the soundbar, please follow the below methods to do the troubleshooting:
1. Replace another input source, like HDMI input and AV input, and check whether the volume of the soundbar will be normal.
2. Try to restore the TV back to the factory settings: press the Home button on the TV remote. Then select Settings Device Preferences Factory Reset.
3. If the TV has internet access, please check if there is a new version of software updated online or not.
Press the Home button on the TV remote, and select Settings Device Preferences About System update Network Update:
If the issue cannot be resolved, please feel free to call the TCL Helpline for further help.