Edit Task
Select a task in the Traffic Statistic (Schedule) Task Manager. 
Click  option in Task Actions pane. 
Perform the steps 1 through 5 as in New Task. While proceeding through the steps, you may add a new report, delete a report, edit report scope/criteria settings, change the export path, e-mail address, change the schedule settings, etc.,
The new settings will be used when the task runs the next time.