You can edit triggers, but cannot change the Before save or After save option or the activity selected on the Trigger When tab.
1. Choose Tools > Administration > Automation Rules.
The Configure Automation Rules dialog box opens.
2. Click the Triggers tab.
3. Select an item Type. The items change based on the selected type.
4. Select a trigger and click Edit.
The Edit Trigger Rule dialog box opens.
5. Make any changes and click OK.
The changes are saved.