Method 1,
If you use the Optical cable connect the soundbar to your TV, make sure the soundbar LED show the white light or OPT, then please press the home (or menu) on the TV remote, go to TV setting→audio (sound)→TV speaker--select external speaker(turn off TV speaker), save the setting, then back to audio(sound setting)---select expert setting---digital audio output(or optical output)---select PCM(some TV called SPDIF or optical), Save the setting, then try again.
Method 2,
If you use the HDMI-ARC cable, please make sure the soundbar LED show the purple light or ARC , then press the home (or menu) on the TV remote, go to TV setting→audio(sound)→TV speaker--select external speaker(turn off the TV speaker), save the setting, then back to audio(sound setting)---select expert setting---digital audio output---select HDMI-ARC(per some TV, please choose CEC, then activate the ARC), Save the setting.
Method 3,
If you hear the noise from video Apps, please disable the Dolby and DTS on your Apps or TVs,this will help fix the issue.
Here is a method for the Netflix：
Step 1, Launch the Netflix app.
Step 2, Select a TV show or movie.
Step 3, While your TV show or movie is playing, press the Down arrow on your remote.
Step 4, Select Audio & Subtitles.
Step 5, Select your preferred audio or subtitle options. (disable the Dolby and DTS)
Step 6, save the settings
Step 7, play the video test the sound
PS: since Netflix have too many different version APPs, so if the above method did not work, we do suggest you click the below link to your TV brand to try again, or use your account to contact Netflix for help:
https://help.netflix.com/en/node/372
Also for the amazon prime video app and others, also please kindly disable the Dolby and DTS, the method is similar to Netflix, please kindly try.