The "Newest Members" island is coded to display just the last 5 members who are approved, and not banned.
This number is defined within the /cache_builders/new_users.php file towards the top. If you need to have the display higher or lower, you could manually edit it. there is no setting within the control panel to manage this, since this is just a small preview to all users, of the last few new members to the site.
Clicking on the "Newest Members" portal box title will display all members, ordered by their join date (Joined), and can further be sorted by its other column items.
https://www.ubbcentral.com/forums/ubbthreads.php/ubb/showmembers/sb/10/page/1
