Another way to see a simpler list of topics:
When you are logged in and there are topics/posts you have not seen, an Unread button appears on the front page. But it disappears when you have read them. Here’s the url, in case you want to leave it open in a browser tab:
https://forum.plaintextaccounting.org/unread
Or, you can jump there by pressing g u.
But again, the meaning of “Unread” may be a bit special and Discourse-y. I believe it’s “unread posts on topics you have shown an interest in”.