1. Go to Settings > Control Center > Customize Controls, then tap  next to Screen Recording.
2. Swipe up from the bottom edge of any screen. On iPhone X or later or iPad with iOS 12 or later, or iPadOS, swipe down from the upper-right corner of the screen.
3. Press deeply on  and tap Microphone.
4. Tap Start Recording, then wait for the three-second countdown. 
5. Open Control Center and tap . Or tap the red status bar at the top of your screen and tap Stop.
6. Go to the Photos app and select your screen recording.
7. Tap and choose YouTube or any app you wish to share to.