Once commenting has been enabled, you can return to the Comments tab, under the People tab, to change the comments reading and writing rules. Changes will apply to all future comments.
Reading Rules:
Anyone: every user that accesses the site can read the comments
All logged in users: only users that are signed in can read comments
Logged in users with access: only logged in users that have access to the specific content through purchases or a subscription can read the comments
Writing Rules:
All logged in users: only users that are signed in can write comments
Logged in users with access: only logged in users that have access to the specific content through purchases or a subscription can read the comments