Some thread titles are bold. others are not?

[Rickles]

I probably haven't searched in the right place, but why are some thread titles, especially in the classifieds, in boldface while others are not? Just curious. Thanks.

 

[David Wilson]

new threads / threads with unread posts show up in bold

 

[Rickles]

new threads / threads with unread posts show up in bold

Thanks.

 

[vernhillbass]

I've posted before and none of my posts are bold.