If you want to edit your smartform response on the web from your desktop/laptop you will need to choose the "Save as completed" save option and then click the submit button.
You will see a pop up message telling you that "You will no longer be able to edit the response on your device. All subsequent changes to this response can only be done on the web. Are you sure? If you click the "Save as completed" button then your response will be locked on your device.
Note the padlock on the response when viewing the response list.