In forum.asp around line 533 you will find this code:
Response.Write "</a></td>" & vbNewLine & _
" <td bgcolor=""" & strForumCellColor & """ valign=""middle"" align=""left"">" & vbNewLine & _
" <font face=""" & strDefaultFontFace & """ size=""" & strDefaultFontSize & """ color=""" & strForumFontColor & """>"
here you can edit the font color ore style (if the admin options are not at your satisfaction)..look at red text:
Response.Write "</a></td>" & vbNewLine & _
" <td bgcolor=""" & strForumCellColor & """ valign=""middle"" align=""left"">" & vbNewLine & _
" <B><font face=""" & strDefaultFontFace & """ size=""" & strDefaultFontSize & """ color=""" & strForumFontColor & """></B>"
Note that there are 4 more places in forum.asp that needs this edit, and that not every letter type will do this bold. Hope it will give you a start.