Many thanks for the help Lynne.
For anyone who might want to do this, the easiest way as Lynne said is to change the CSS. You find it toward the bottom of the Main CSS page in "Additional CSS Definitions."
Toward the bottom of the code in that box, you'll find something like this:
Code:
/* ***** de-emphasized text */
.shade, a.shade:link, a.shade:visited { color: #333ccc; text-decoration: none; }
Add text attributes here to format the headers of your user profiles fields.