When creating a custom report you can select the order in which the columns are shown in the report output. By default columns are shown in the order presented in the Columns step of the Report Wizard.
To change the column ordering in a custom report
Next step: Select Custom Report Column Filters
Previous step: Select Custom Report Grouping Information.
Additional Information
Select Custom Report Output Options and Access Permissions
Select Optional Tables for Custom Reports (Advanced)
Select Custom Report Columns to Sort on (Advanced)