Why is the message sent by WeChat not displayed on the mobile phone screen? How to set it?

Take OPPO R9S mobile phone as an example, the setting method is as follows:

First, find the "Settings" item on the mobile phone desktop, and click Enter.

2. After entering the settings, find the column of "Notification and Status Bar" and click Enter.

Third, after entering, find the column of "Notice Management" and click Enter.

4. After entering, find the project "WeChat" and click Enter.

5. After entering WeChat, turn on the switch of "Allow notification" column, and then turn on the switches of "Show on lock screen" and "Show on top of screen", so that the mobile phone screen will be displayed when WeChat comes with information.