I'm not sure if this answers your question but this is how I do it:
Click on 'Groups' and go to the group that you own and wish to update. In the middle of the page you'll see 'View Edit Group' - click on 'Group'.
Select the option 'People - manage group members'.
Select the user from the list and then choose the required option from the drop down list that appears just above the list of people in your group.
Click 'Update' and the changes take effect.
Answers
I'm not sure if this answers your question but this is how I do it:
Click on 'Groups' and go to the group that you own and wish to update. In the middle of the page you'll see 'View Edit Group' - click on 'Group'.
Select the option 'People - manage group members'.
Select the user from the list and then choose the required option from the drop down list that appears just above the list of people in your group.
Click 'Update' and the changes take effect.