[@robkk Moderator 11 years, 9 months ago]

it could be just making the font-size smaller.

copy this CSS anywhere you can put custom CSS

#bbpress-forums div.bbp-forum-author a.bbp-author-name, 
#bbpress-forums div.bbp-topic-author a.bbp-author-name, 
#bbpress-forums div.bbp-reply-author a.bbp-author-name {
font-size:12px;
}