How to make a security strong

For your screen lock passcode choose a 6 digit code that someone who knows you won’t be able to guess; that is, don’t use your birthday or that of anyone in your family, don’t use your address or phone number, etc.

For your Apple ID create a strong password, 8 characters minimum, 12 or more better. Google for ideas on how to create a strong password.

To further protect your Apple ID add 2 factor authentication—>Two-factor authentication for Apple ID - Apple Support