Select Address (Membership) Utilities under Membership.
This function is NOT designed for use with Sunday School classes, just school grades. Sunday School class membership is maintained using Individual List Maintenance.
Click on the eyeglasses icon to view Individuals in a particular grade. The Individual Record window will open with all students currently in the grade listed in the Find Results portion of the window. If you have students who have not changed grades with the new school year, you can change their Individual Records to the previous grade before doing the mass update. Click the Update button to move individuals from the Current school grade to the New school grade.