How to set a Screen Time passcode on an iPhone or iPad
With a Screen Time passcode, you can ensure the settings you choose for your child's device remain in place. That means the passcode must be entered before changing Screen Time settings. When a Screen Time passcode is enabled for a child's device, you receive a notification any time it's used on your child's device.
A Screen Time passcode isn’t the same as the passcode you use to unlock your device. It’s important to keep track of your Screen Time passcode because you need it to change the Screen Time settings for your device or a child’s device. You can change or remove a Screen Time passcode at any time.
If you use Family Sharing to manage a child’s Apple Account, the Family organizer needs to set the child's Screen Time passcode on their own device, not the child's device.
Learn what to do if you forget your Screen Time passcode
Set a Screen Time passcode for your child’s iPhone or iPad
Open the Settings app, then tap Screen Time.
Scroll down and tap your child’s name under Family. If you don’t see your child’s name under Family, make sure you’re both signed in to your own Apple Account and have Family Sharing set up.
Tap Manage Screen Time, then tap Lock Screen Time Settings.
Enter a 4-digit passcode, then enter the passcode again to confirm.
Set a Screen Time passcode for your iPhone or iPad
Open the Settings app, then tap Screen Time.
Scroll down, then tap Lock Screen Time Settings.

Enter a 4-digit passcode, then enter the passcode again to confirm.
To add a Screen Time Passcode Recovery, enter the email address or phone number and password for your Apple Account.

It’s recommended that you don’t skip adding a Screen Time Passcode Recovery. That way, if you forget your Screen Time passcode, you can use your Apple Account to reset it. If you have more than one Apple Account, you must use the same account you entered when you first set up the Screen Time Passcode Recovery.
It's important to remember the Apple Account that you used for your Screen Time Passcode Recovery because without it, you won't be able to remove or reset your Screen Time passcode, and Apple won't be able to provide that information.
Learn more about managing a Screen Time passcode