Access Settings-Discussions Tab

New Comment - select user groups that will be allowed to comment reviews. (Review discussions need to be enabled in Configuration Settings => Reviews).

Moderate (Hold for approval) - New Comment - comments of selected user groups will be held for approval by admin.

Edit Comment - choose which user groups will be able to edit comments. Registered and Author can edit only their own comments. Editor and above can edit all comments.

Delete Comment - choose which user groups will be able to delete comments. Registered and Author can delete only their own comments. Editor and above can delete all comments.