bbPress.org

Our website is currently down.
However, I have been using WordPress 4.5 with BBPress 2.5.8.

I do not want my forum to be accessible to the public or through Google searches.

Our website was developed to have usernames and passwords to access a log-in area where the forum is held.
The settings for the forum were set as:
Status: Open
Visibility: Public

We’ve since found out that topics can be found on Google with these settings. Our web developer says that the settings don’t matter.

So, my question is: How do we create a forum that is not accessible to the public/Google?