Yeah, I don't like it either. I'll come back to that in a moment.
As you can see there are big changes to the forum. The first issue you might have is logging in. You will need to use your Displayname and not your Username from the old forum to login. Your Displayname is the name it shows on your posts. The new forum software only uses one name, and I thought it would be better to use Displayname in case anyone didn't want their username made public. You can also your email address that you registered with.
Anyway, the forums are very bland looking and ugly right now. And there are a lot of changes that I don't like. Your "friends" are now gone. There is a follow feature that is similar. A lot of things are less intuitive now, but I think the software is more for a site running a store, or selling things, and not so much just a discussion forum anymore. I kept the old version of forum software running as long as I could but finally I needed to update.
I'll try to make the forum 'pretty' again. If you have any issues, please post in the Helpdesk forum. You can post there even if you can't log in.