Bro, first drop down notification panel and click on secure folder and turn on secure folder.. now get inside secure folder and click on add apps/files add your desired apps or files now click at 3 dots at the top select settings here you will gonna find all lock and security features
NOTE: YOU CAN USE BIOMETRICS ONLY TO LOCK OR UNLOCK SECURE FOLDER..CAN'T BE USED FOR THE ADDED APPS..
