Students accessing the online forum

During my last class,I saw a student on this forum and getting an answer to a puzzle. I thought that students weren’t able to access this forum. If there is a way to turn off a setting for this, please let me know. I see this being a huge issue. I have never seen anyone be able to access the forum before.

Thanks!

It is an open forum, so students also have access. I don’t think there is a way to turn it off.