bbPress only allow Admins to create forums and topics

hi : We only want WP Admins the ability to create bbPress topics and forums.
We need a simple way to set all existing users to: Not allowed create forums, or topics.
All existing users should only be allowed to Reply to topics.
Is there a "one-click" or simple way to set ALL existing users to: forum role = "spectator"
What is the easiest way to achieve this?

Access active until 10:49pm in 3 days
Please advise...