Why won't my phone lock even when I've already set up a screen lock password?

If you've set up your screen lock PIN, password, or fingerprint scanner—if your phone has one—and the phone still won't lock, you may have enabled Smart Lock to always auto unlock the phone when a trusted device is connected such as a Bluetooth® headset.

• Turn off Bluetooth, or remove the Bluetooth device from the Smart Lock trusted devices.
• Or turn off Smart Lock.

For more details, see What is Smart Lock and how do I use it?.