For all the PagingToolbar objects on the Forum and User tabs, use PagingToolbar.update() to force the container to rewrite the text with new store details!
http://www.sencha.com/forum/showthread.php?115950-Grid-Paging-Toolbar-problem&highlight=PagingToolbar total update
http://www.sencha.com/forum/showthread.php?114168-Total-Row-Count-on-PagingToolbar-can-be-incorrect&highlight=PagingToolbar total update
http://www.sencha.com/forum/showthread.php?116861-Updating-the-totalProperty-of-the-pagination-bar&highlight=PagingToolbar total update