Use your phone’s app lock or screen pinning feature
Set up a device passcode, PIN, pattern, or biometric lock
Use parental controls in Google Family Link
Turn on Restricted Mode in the YouTube app
Sign out of YouTube when not in use
Use a third-party app locker if your device supports it
Disable app installation from unknown sources
Restrict YouTube access through your router or DNS settings
Use Screen Time or Digital Wellbeing limits
Lock the device itself before handing it to others