The only way to keep watching videos on your vintage device is to manually sideload an of YouTube. This is where the search for a "YouTube IPA file for iOS 9.3.5" begins.
Required for the initial setup and data loading. How to Download and Install the YouTube IPA download youtube ipa file for ios 9.3.5
For a new user, or someone who wiped their iPhone 4S for nostalgia, the App Store will simply refuse to serve the final working build of YouTube. The official YouTube app for iOS 9.3.5 (version 10.11.11546, to be precise) is effectively abandonware. It exists, but Apple has hidden it behind a digital velvet rope. The only way to keep watching videos on
When you download an app from the App Store, Apple sends an encrypted IPA to your device. However, because Apple removed old versions of YouTube from its servers (for devices on iOS 9), you cannot download the last compatible version natively anymore. You need a third-party source providing the . How to Download and Install the YouTube IPA
: Use an Apple ID that has previously downloaded YouTube.
Result: YouTube stays on your device forever, even after reboots.