unable to change my lock from swipe to pin

[AC Question]

When I go to lock screen and select screen lock type (currently just set to swipe) the correct page comes up and the choices are there including pin but I cannot select pin because a message immediately come up to cover the pin selection prompting you with a fingerprint screen. Then you have the choice of hitting cancel or backup password. If you select cancel just takes your to previous lock screen. If you select backup password takes you to screen to enter a backup password. Don't know what would happen if I had a backup password to enter but it doesn't make sense. I know I should be able to go the the pin screen directly if the message wasn't flashed onto my screen. Please let me know of a fix for this.

 

[epi23]

What phone do you have?