We use a number of custom fields that I like to sort by. I used to have the ability to display the fields I wanted via the Change Column Display button. That button seems to have disappeared and I'm unable to set up the visible fields I'd like to see on a Group or Segment view.
We recently released the ability to change the columns that get displayed within the audience section. You can add up to 10 fields to be displayed while viewing all contacts, the members of a group or segment, and search results. You can also sort by the columns that that you add.
Please let me know if you have any questions or feedback!