I can't enable firewall on Avast Mobile

[Marios1441]

I have the latest version of Avast Mobile Security Premium for Android and i can't enable Firewall. A message says
the phone is not rooted (but it is) or i must change the Firewall's permisions. Also how do i change the firewall permissions? What should i do to fix it?.

 

[Hadron]

Have you given Avast superuser permissions? Check your superuser app (Superuser or SuperSU, whichever you have) and make sure you haven't denied the permission previously, and undo it if you have.

 

[Marios1441]

Have you given Avast superuser permissions? Check your superuser app (Superuser or SuperSU, whichever you have) and make sure you haven't denied the permission previously, and undo it if you have.

I already have root manager. Is called Kinguser. Avast already have root permission in this app. What the Superuser and SuperSU apps do? I can't see
Avast on the app list.