In order to edit your notification, please navigate to your notifications and click Edit. You can also access Edit notification button in the Show view.
You can edit all the fields in your notification. In case you would like to proceed with a result of your update, click Update.
To see how the end result of the notification will look like you can exit Edit Notification mode, find the notification you have just edited in the list and click Show or Send Test Email. Please note test mode will only show the dummy data and not the real values. It will not show the attachment either.