Ranks and Group Icons

Hi fellows,

I seem to have misunderstood the Ranks (custom image) and Group Icon settings:

We used to have Ranks with star images from 1 to 5 stars, e.g. in yellow color for normal members
Some groups had own stars, e.g. in green color.

The ranks are set by number of content items, which is fine. But the group icons don't override rank images nor can I set custom ranks for specific groups.

How can I accomplish that?

Thank you,
Thomas