Download the YouTube app on that newer device to "link" it to your account history.
Networking
To help you decide which method is best for your situation, here is a quick comparison: install youtube ios 1257
If the app remains unstable on older hardware, the web version is often more reliable. Open and go to m.youtube.com. Tap the Share icon (square with an up arrow). Select Add to Home Screen . Download the YouTube app on that newer device
Sometimes, older versions of Safari on iOS 12.5.7 struggle to render modern web video players efficiently. If Method 2 feels slow or buggy, switching to a dedicated third-party browser can resolve playback issues. Top Browser Alternatives: Tap the Share icon (square with an up arrow)
iOS 12.5.7 is an old operating system, and some App Store certificates may be out of date. Go to Settings > General > Date & Time , turn off "Set Automatically," manually set the date to a few years ago (e.g., 2020), then try the App Store again. If it works, switch back to automatic date and time afterwards.