Tap the immediately next to the application logo.

Open Safari , go to youtube.com . The mobile site works decently on iOS 9.3.5 and may be more reliable than the old app.

The significance of iOS 9.3.5 lies in its status as the "end of the line" for some of Apple’s most beloved hardware. The iPhone 4S and iPad 2 were transformative devices that defined a generation of mobile computing. However, as these devices aged, they lost the hardware capability to run Apple’s modern operating systems. While the hardware often remains functional—screens light up, speakers play sound, and processors hum—the software ecosystem has moved on without them. The App Store, once a marketplace of infinite possibility for these devices, now frequently displays the frustrating notification: "This application requires iOS 10.0 or later."

This will install the last YouTube version made for iOS 9 (likely from around 2017–2018). Note: Many features will be broken or missing today, and you'll see constant update prompts.