When you edit a user, what you should be able to see on the right is a dropdown for Primary Usergroup, and checkboxes for secondary usergroups. If a user has both a primary and secondary usergroup, a second dropdown will appear labeled 'display usergroup', which if I'm right will be the usergroup whose visible styling will appear on the poastbits:
But it looks like you set it already. I think Flint should have a site staff set as primary usergroup though, because of permissions and shit (idk if he still has the same permissions now).
As for setting the user title colour and title position, that'll take a template edit, and it'll probably be applied for every user
. You'll have to tell me exactly which title goes where though, my brain hurts trying to differentiate between the three billion titles everyone has now.