How can I specify markup colors for secondary groups?

[Joey Link]

What I'd like to do is make it so I can change the markup for the usernames of members of a secondary group. Right now all my members except administrators are members of the Registered Users primary group. When people donate, they get put into a secondary group. I'd like to make their usernames change from the default to red.

I clicked the 'Can override primary group title/markup', which to my understanding makes it so the secondary usergroups markup settings override that of the primary group, but it's not working like that. Isn't that the purpose of that option?

I'd love some help guys.