This tutorial will show you how to make your forums viewable to logged in members only. Guests and bots will not be able to see the forum itself, nor it's contents.
1. Login to your Administration Control Panel.
2. Click the "Permissions" tab at the top.
3. In the left menu, under "Forum based permissions," click "Forum permissions."
4. In the "Select a forum:" field, select all of the forums that you'd like to make private. You can select more than one by holding down the CTRL key on your keyboard. Press "Submit."
5. Now, select the groups that you want the forums to be hidden from. This would likely include "Bots" and "Guests." Again, you can select more than one group by holding down the CTRL key on your keyboard. Click "Edit permissions."
6. Each of the individuals forums will now be listed with the group listed under each forum, as well. Their current role will be displayed. For each "Role:" box, select "No Access." Once all of them say "No Access," click "Apply all permissions."
The forums you selected will no longer appear, in any form, to bots or users who are not logged in.
It is worth noting that this will severely hamper your ability to be found through search engines as you are effectively telling them that they can't index any of your content. So, it should only be utilized when you have a specific reason for doing so.
Thank you for reading.