How to change the words 'Forum' and 'Last Post'?

Hello, thanks to the forum search, and other support forums I've found it is possible to rename elements on forumotion. I've effectively managed to exchange my category titles with the word 'Level' using jquery's replace with. I can't seem to do the same with table header forum (th.forum) or table header last (th.last). What's the problem?

http://wockeez-internationa.forumotion.net/

Hi,

This code should work, add it for home page...

Code:

$(function(){
  $('.index-box th.forum').text('NEW NAME FOR FORUM');
  $('.index-box th.last').text('NEW NAME FOR LASTPOST');
});

Thanks, I was using the wrong code I guess.