I have promoted Prosilver-Forumosa to be the default theme on the forums, as originally announced here: http://flob.me/p1199834
You can switch back to the original Forumosa-theme from the User Control Panel (http://forumosa.com/taiwan/ucp.php) but do bear in mind, that Forumosa style will not be supported going forward. So, improvements and certain features will not be available there — meanwhile the prosilver-forumosa theme will be kept up to date. And if the original Forumosa theme is suspected of being a security risk because it is less advanced than prosilver-forumosa, it will be immediately retired.
Let us know any questions, comments, and suggestions you may have here or at the feedback discussion on the forums