[ozzy47]

That is controlled by the stylevar, forumbits_text_color, found under the group, Forums.

Note that changing that stylevar will also change some other elements color also.

If you don't want to do that, then add this to your additional.css

/* Start change forum description color */
.forumbit_post .forumdescription {
    color: red !important;
}
/* End change forum description color */

And change red as desired.