This identity validation is extra to those already known that block the cell phone screen, since it works for the application in a timely manner, beyond the screen being unlocked. In other words, even if WhatsApp is blocked you can answer calls, for example. The way to activate it is to go to Account> Privacy> Fingerprint lock. Then you must mark in what time it is blocked: immediately, in 1 minute or after 30 minutes. Then you can enable message notifications to be seen, without ente...