If you cannot get the app to work, the is to use Safari. Modern web browsers on iOS 12 can run the YouTube mobile website, which has improved significantly. Open Safari: Go to youtube.com .

iOS 12.5.7 devices have limited RAM (often 1GB or less). To improve playback, lower the video quality from 1080p to 480p or 720p by tapping the gear icon inside the video player.

Once you've updated your device, try installing YouTube from the App Store.

Have you successfully installed version 1257? Let us know in the comments which iPhone model you are using and how the battery life compares!