Unfortunately VBulletin had a lot of security exploits, which is why it got hacked twice in as many weeks. There was also a lot of repeated behind the scenes issues regarding database corruptions and such, which is why we switched systems. Like everything, it’ll just take some getting used to, though I understand frustrations with new interfaces.
Like John said, the reason old posts show up as “latest” is because they were bumped. And the reason it looks like nothing changed on those posts is that bump just also happened to be spam, so the “update” was hidden from public view.
I did some googling to see if there is a way to automatically remove a topic from ‘latest’ if the bump is deleted/made hidden, or if there is a way to maybe have per-user custom layouts of some type so users, like yourself, could see the forum looking more like a traditional forum, but not seeing much so far. Joseph is the Discourse Master, though, so he would know more about the ins and outs than I do.
(Personally, I had the hardest time finding new posts in the old system, which is one of the reasons I, unfortunately, didn’t interact as much as I should have. I always had to click every single topic to check for new posts. And then half would be an old post was bumped with spam. So I really like that any posts that are added or updated are all in one place, now, but again, I can see how it may also be confusing when it doesn’t look like anything changed).