unauthorized users

There are no devices attached to your phone. You may be sharing your Apple ID account with other devices; to see go to Settings/[your name] and it will list the devices on your Apple ID account. You can tap on any of the listed devices and remove it from your account.

You've posted three questions about iOS security. Are you seeing something specific that is causing you concern? I think you'll find you get more satisfying answers if you explain exactly what's going on.

Only those that have the device in their own hands.