You can use the Edit Encryption Key dialog to edit the description of a Encryption Key resource for the target AWS platform.
In the Web Interface toolbar, select the Platforms tab.
Select the platform, then click Edit.
Under Associations, select the Encryption Keys tab, then click Edit (or double-click the encryption key) to open the Edit Encryption Key dialog.
Modify the Description for the Encryption Key resource.
Click Save to update the Encryption Key resource.
Click Close to exit the dialog.