I have 4 Apple TV in my house.

Hello, RCS.

Thank you for visiting Apple Support Communities.

I would need clarification on what you mean by you can not see YouTube to provide a better answer. However, it sounds like either the YouTube app is hidden/missing or you are having streaming issues. I have included a couple troubleshooting articles for both scenarios below.

Resolve network or streaming issues

• Troubleshoot Wi-Fi networks and connections.
• Switch between wired and wireless networks.
• Learn how to resolve issues streaming content from third-party content providers. Learn more about third-party content providers.

If you're streaming content from a computer or iOS device using Airplay or Home Sharing, try these steps:

• Resolve issues with Airplay and Airplay Mirroring.
• Learn how to use Airplay Mirrorring.
• See how to set up Home Sharing.
• Troubleshoot Home Sharing issues.

Apple TV: Basic troubleshooting

Apple TV: Arranging and hiding icons on the main menu

Cheers,

Jason H.