If the audio is abnormal when using the HDMI IN port, please follow the below methods to do the troubleshooting:
1. Check whether the TV works in the right input mode. If the device connected to the HDMI1 port on the TV, then switch the TV to HDMI1 mode.
2. Change the HDMI cable and check the issue if you have a spare one.
3. Change to another HDMI port of the TV and check if the issue has been solved.
Please note that it requires plugging the device to the correct port with the HDMI 2.1 cable if you play the 8K video.
4. Connect the TV to another device if you have a spare one.
5. Try to restore the TV back to the factory settings.
Press the Settings 
button on the TV remote, then select Settings --> System --> About --> Reset --> Factory Reset:
If the problem can’t be resolved, please feel free to call the TCL hotline for further help.
