If possible, upgrading to a newer iPhone or iPad (even an iPhone 6s or newer on iOS 15) will give you full YouTube support and security updates. Reply with the exact error message you see in the App Store, and I can offer a specific fix.
For iOS 10.3.4, the Safari web app ( m.youtube.com added to Home Screen) is often faster and more reliable than the old native YouTube app. Only use the App Store version if you specifically need sign-in features that the website breaks. A Note on Device Security iOS 10.3.4 is from 2019 and no longer receives security patches from Apple. While YouTube still works, your device is vulnerable to known exploits. Consider using it only for media playback and avoid banking, email, or sensitive logins. youtube ios 10.3.4 download
If you are using an older Apple device—such as the iPhone 5, iPhone 5c, or iPad 4th generation—you may be stuck on iOS 10.3.4. This version is no longer supported by the latest version of YouTube, which requires iOS 14 or newer. If possible, upgrading to a newer iPhone or