For better security, you can set a passcode that must be entered each time you turn on or wake up iPod touch.
Set, change, or turn off the passcode. Go to Settings > Passcode.
To adjust when iPod touch automatically locks (and then requires the passcode to unlock), go to Settings > Display & Brightness > Auto-Lock.
Setting a passcode turns on data protection, using your passcode as a key to encrypt Mail messages and attachments stored on iPod touch, using 256-bit AES encryption. (Other apps may also use data protection.)
Increase security. Turn off Simple Passcode and use a longer passcode. To enter a passcode that’s a combination of numbers and letters, you use the keyboard. If you prefer to unlock iPod touch using the numeric keypad, set up a longer passcode using numbers only.
Allow access to features when iPod touch is locked. Go to Settings > Passcode. Optional features include:
Today View (see Notifications)
Notifications View (see Notifications)
Reply with Message (see Send and receive messages)
Siri (if enabled; see Make requests)
Wallet (see Wallet overview)
Home Control (see Home overview)
Reply with Message (see Make and answer calls with FaceTime)
Allow access to Control Center when iPod touch is locked. Go to Settings > Control Center. See Control Center.
Erase data after ten failed passcode attempts. Go to Settings > Passcode, then tap Erase Data. After ten failed passcode attempts, all settings are reset, all your information and media are erased, and you must restore your device from a backup or set it up again as new.