[tbworld]

It wasn't completely clear what section you were trying to change. I am guessing the forumhead category header text/link.

Add this CSS to your additional.css and let me know if this is the right area.

/* forumHead category title */
.tcat1 a:link, .tcat1_alink {
    color: red;  /* changed the grey to red */
}

/* hover */
.tcat1 a:hover, .tcat1 a:active, .tcat1_ahover {
  color: yellow;
  text-decoration: none;
}