Quick answer

Ensure your LG OLED TV is set to the correct audio output (eARC).
Check that your HDMI cable supports eARC; consider using a Certified Ultra High Speed HDMI Cable (paid link).
Restart your TV and any connected devices.
Update the firmware of your TV and sound system.

Symptoms

Verify that the TV is not muted or set to a very low volume.
Ensure the audio output settings are configured for eARC in the TV’s settings.
Confirm that the HDMI cable is securely connected to both the TV and the sound system.
Check if other apps on the TV produce sound.

Check Audio Settings:
- Go to the TV’s settings menu.
- Navigate to the audio settings.
- Ensure the output is set to eARC or HDMI ARC.
Inspect HDMI Connection:
- Disconnect and reconnect the HDMI cable.
- Ensure the cable is plugged into the HDMI ARC/eARC port on both the TV and sound system.
Update Firmware:
- Check for software updates on your LG OLED TV.
- Update the firmware of your sound system if applicable.
Restart Devices:
- Power off the TV and sound system.
- Unplug them from the wall for a minute.
- Plug them back in and power them on.
Test with Different Apps:
- Open various TV apps (like Netflix or YouTube) to see if sound issues persist across all apps.

Try using a different HDMI cable to rule out cable issues.
Connect a different device to the HDMI ARC/eARC port to see if sound works.
Reset the TV to factory settings as a last resort. Be sure to back up any important data first.

Why is there no sound from my LG OLED TV apps?
- It could be due to incorrect audio settings, a faulty HDMI cable, or a software issue.
How do I know if my HDMI cable supports eARC?
- Look for cables labeled as "Ultra High Speed" or check the manufacturer's specifications.
What should I do if the sound only works for external devices?
- Focus on the TV’s audio settings and ensure they are configured for internal apps.
Can a firmware update fix audio issues?
- Yes, updates often include bug fixes that can resolve audio problems.
Why does audio cut in and out?
- This could be caused by a poor HDMI connection, a faulty cable, or interference from other devices.