on the "Show unread posts since last visit".
They should. Maybe the title show be "Show new posts since last visit". While technically, I've read the post since I wrote it, on the other hand it is a new post.

This is especially true for "For Sale and Wanted to Buy" posts. If I add a post to it, it should show up as new, whether or not I wrote it.

I made a reply to a For Sale ad I had placed, in order to have a fresh reply that would bring the ad back to the top of the listing. It's a common practice, with the reply just having the initials "ttt", meaning "to the top". I do it about once a week as opposed to some people doing it daily or more often.

When I do this, I do not see the ad, the thread in my "unread" listing.