This administration interface reflects the Message board web part's properties. When you add the web part to a page, you can set its properties in the web part properties dialog. When first message is added to the board, the message board is created in this section of the administration interface. At this point, changes made to the web part properties have no effects and you have to make all changes only in this section!
Editing message board properties
Remember that once the message board is created (after first message or subscription), you cannot make changes to these settings in the web part's properties. You can only modify values in this section of the administration interface.
The administration interface for editing message boards is divided into five tabs, whose descriptions can be found on the child pages of this context help page, accessible via the tree on the left.
Detailed information about the Message boards module can be found in Developer's Guide -> Modules -> Message boards.