To change your restrictions passcode on an iPhone, you'll need to go into your Settings. Where you go from there depends on your iOS version.

Losing access to your iPhone’s Screen Time passcode can be a significant inconvenience, especially when it limits your ability to manage app usage, content restrictions, or device settings.

Before you enable Downtime, go to Settings > Screen Time > Limit Usage > Always Allowed. From here, choose essential apps ...

Remember, the longer and more complex your passcode, the tougher it is for prying eyes to sneak a peek as you type it in. Also, consider investing in a privacy screen. These screen protectors limit ...