Use the Group Expert to specify how fields will be grouped on your report. You can also use the dialog box to reposition groups and to edit the criteria used for triggering and sorting groups. This dialog box appears when you right-click a Group Header in the Report Designer or Group Name in the Field Explorer and select Group Expert, or when you right-click in the Report Designer, point to Report and choose Group Expert.
When you enter a group, that group appears directly above and below the Details section. When you add a second group, it appears between the Details section and the first group. The third group is between the Details section and the second group, and so on. Thus, when you look at the Report Designer, the Group Header for the first group is the top group header, and the Group Footer for the first group is the bottom group footer.
This Group By list reflects the group footer order of groups; the bottom group in the list is the first group, the group next to the bottom is the second group, and so forth.
When you select a group in this list, the program activates those buttons that apply to the selected group.
Change Group Options Dialog Box | Grouping, Sorting, and Totaling Data