Why can't I edit an original post to update it when items sell or add new items? I am a paid member.

You can't after an X amount of time. Just the way it is.

OSO members with any membership level can edit posts for 72 hrs.. Only mods can edit after the 72 hrs.

This is most likely a good thing for buyers and sellers if any disputes come about.

But it forces people to keep making new ads and pushes things back 8 pages. It is what it is. I see your point.