You can only modify alerts that you have created and that are displayed in the Alert List when you select the My View tab. You do not need to re-subscribe to a modified alert because all changes made to an alert automatically apply to the subscription.
To modify an alert:
Log on to Performance Scorecard.
In the Viewer, select Browser View .
Expand Alerts.
The list of alert types is displayed.
Click to expand the alert type, and select the alert you want to modify.
For example, to edit a measure variance alert, click Measure Alerts, and then Variance in Range.
Click Edit.
The Alert Setup page for the selected alert type is displayed.
Modify the attributes for the alert.
Click Save.