This feature overcomes the BBPress limitation of private forums.
Course Forums are BBPress forums which are connected to a course in Course Settings section.
Consider following user cases :
Use case : Forum Type : Course Forum Privacy : User can access the forum/topic
1. Non Logged in User : Public : Disabled : Yes
2. Non Logged in User : Private : Disabled : No
3. Logged in User : Public : Enabled : Yes is user is subscribed to the course to which the forum is connected , No is user is not subscribed to the course.
4. Logged in User : Private : Enabled : Yes is user is subscribed to the course to which the forum is connected , No is user is not subscribed to the course.
Note : When this feature is enabled. When user views a topic, the control will look for the parent or parents forum of the topic and check if this forum is connected to a course, if the forum is connected to a course and the user is also subscribed to the course only then she'll be able to access the forum,