Not all achievements give out forum titles. Achievements that have a prize associated with them have a little star on the tier, and you can click on it to see the reward. Some rewards are items, and some rewards are forum titles.

Forum signatures are taking a while to update, and there's an image there when I look at it, so it's gone through!

You should see achievements in categories if you click on "All" (next to Earned in your screenshot)