Apple and Google have long since moved on from iOS 9.3.5, which means modern versions of the YouTube app are no longer compatible with this older operating system. For users, this translates to a simple, frustrating reality: the App Store will either refuse to install YouTube or the last compatible version will display a "Loading error. Tap to retry" message. This is because YouTube's backend servers no longer communicate with the outdated API in the last official app.
The official YouTube app now requires iOS 16.0 or later .
Restores the ability to search for videos and play them. Preparing Your iOS 9.3.5 Device
Tap the . When prompted that the current version requires iOS 10+, select Download to install the last compatible version. Method 2: System File Version Spoofing (Jailbreak Required)