Click on the Group Box and you should see it highlighted i.e eight blocks seen at intervals on the group box. Then right click and select Properties. You can also double click and go to the properties.
I am not sure if 8.0 has this, but in 8.10 one can view the tree view of fields in FDA like those in UBE. Then select the group box from that list and change its property. A cool feature, I must say.