If you must sideload, proceed with extreme caution:

IPA files are used for installing applications on iOS devices. To download a YouTube IPA file for iOS 9.3.5, users typically look for third-party sources or repositories that host IPA files. Some popular sources include:

However, I can offer a short informational essay on the topic:

. When prompted to "Download an older version of this app," select

: Use an Apple ID that has previously downloaded YouTube on a newer device. On your iOS 9.3.5 device, go to the App Store > Purchased . Tap the cloud icon next to YouTube.

If the official app remains broken, legacy communities use custom tweaks to repair playback and signing in.