http://lists.uua.org/mailman/admin/listname/archive is the home page for your "Archiving Options." For most lists, the answer to "Archive messages?" should be "Yes."

Be sure your list's archives are private (viewable only by subscribed members). Answer "private" to the question, "Is archive file source for public or private archival?" then click the "Submit Your Changes" button. The only lists that should have public archives are announcement-only lists that act as newsletters.

The other options on this page should be fine using their default settings.