Portal - Enable Case Deflection

Hi all, 

I would like to know how to enable case deflection on the self-service portal for customers.

Is it enough to create the HelpDesk/CaseDeflection/Enabled site setting and set it to true?

I did it but seems nothing changed on the create case procedure on the portal.

Any suggestion?

CRM Version: Dynamics 365

Portal Version: 8.2

Thanks in advance.