In the report output, columns are displayed in the order that you arrange them in the report designer. You can move a column by clicking and dragging it to a new position on the screen. The dotted line indicates where the column will be positioned if you drop it. The green icon with an arrow indicates that you can drop the field in that position:
If you can't drop a column in the position you have dragged it to, a red error icon is displayed:
Note: Columns that have grouping applied must be positioned on the left side of the report. You can't place a grouped field to the right of a non-grouped field.