must register to the forum

is there a way to make it so people must register before they can read anything on the forum?

No there isn't.

Actually there is a way this can be done.
 
 Admin > Boards > Modify > (Then where it says "Allowed users" turn on "Guests" and everything else off.) > home and your done.
 
 What i did is left one board saying "You must be registered to the forum to go futher" and only guests can see it my other group members cant.

Shouldn't this be a normal global feature on any forum? No guest viewing? This is concerning.

Shouldn't this be a normal global feature on any forum? No guest viewing? This is concerning.

No, it is normal that Guests can view the forum/boards/posts.   Board and Permissions Settings allow you to decide what Membergroups can see what on the forum.