Why didn't Huawei nova9 A9 unlock the application when the application lock was opened?

Huawei's mobile phone, the application can not lock the information screen immediately after exiting with a password. The reason why Huawei's application lock does not lock immediately after exiting may be the setting problem, or it may be that the application lock can only take effect after pressing the power button to lock the screen. The design of the application lock is that when the screen is opened, the application lock only needs to enter the password once, and then re-enter it after exiting the application, without having to enter the password again. Press the power button to lock the screen, and the application locking function will take effect again.