I have the 4k Apple TV 3rd generation. I have hdmi cable from Apple TV to my LG soundbar (S95QR). In hdmi1 in. I have the hdmi out from the soundbar to my LG tv. As per instructions on this Apple page. No sound at all.

Hello Danman7000,

Welcome to Apple Support Communities. 

We understand that you have connected your Apple TV to your LG sound bar but there is not sound. We are happy to help.

Please try the steps here as they may help: Use HDMI ARC or eARC with your Apple TV 4K - Apple Support

"Turn on HDMI ARC or eARC

1. Set up your single or stereo pair of HomePod or HomePod mini speakers as the default speaker(s) for Apple TV. 
2. Go the Home screen on Apple TV and select Settings > Video and Audio > Audio Output. 
3. Under Default Audio Output, make sure that the room with HomePod or HomePod mini is selected.
4. Under Audio Return Channel, select Play Television Audio. You'll know ARC or eARC is turned on when it says On (ARC) or On (eARC).

If HDMI ARC or eARC isn't working as expected

• If you can't set up HomePod or HomePod mini as the default speaker for Apple TV, make sure that your HomePod or HomePod mini and Apple TV are added to the same room in the Home app. Then try to set up your HomePod or HomePod mini as the default speaker for your Apple TV again. 
• Make sure that your TV supports ARC or eARC. You can check by seeing if there's an ARC label next to your HDMI port, or you can contact your TV manufacturer.
• You might have to turn on ARC, eARC, or HDMI-CEC in the settings of your TV. Check with your TV manufacturer for details. 
• Unplug the HDMI cables from your TV and Apple TV. Then plug the cables in again and try to use ARC or eARC. "

Let us know if you have further questions.

Take care.