Last updated: 2019-02-18

Source: https://support.freshdesk.com/support/solutions/articles/225180-how-to-setup-private-forums-

You can restrict the visibility of forums to specific customers or keep it internal to just your agents, if needed. While creating a 'New Forum', you would be able to select the 'Visibility' to - All Users, Selected Companies, Agents or Logged-In Users. Once the visibility is set, it would apply to any Topic added under this Forum.