How people have historically attempted to install older IPAs (for context)
Security and legal risks
When Apple released iOS 6, they removed the native YouTube app from the operating system, directing users to download the standalone YouTube app from the App Store. While this allowed for faster updates, it created a long-term dependency. As Google improved YouTube, they dropped support for older iOS versions.
Download and open Cydia Impactor on your Mac or Windows computer. Connect Device: Plug in your iOS 7.1.2 device.
Launch Filza and navigate to the root directory: /var/mobile/Containers/Bundle/Application/ . Locate the folder and open YouTube.app . Scroll down and tap on the Info.plist file.