For iOS 10.3.4, you should target legacy versions or modified versions like YouTube++. Archived IPA Versions Internet Archive maintains a collection of YouTube IPAs. Version are often recommended for legacy devices.
: A third-party client available on the App Store that often supports older iOS versions. If you'd like, I can help you find: download youtube ipa file for ios 10.3.4
: Open Cydia and download the Filza File Manager . For iOS 10
: For iOS 10.3.4 (commonly iPhone 5 or iPad 4), use a tool like h3lix . For iOS 10.3.4