If you edit your /includes/modules/payment/authorizenet_aim.php file, around line 379 you can insert an additional line as shown here:
Code:
// If the response code is not 1 (approved) then redirect back to the payment page with the appropriate error message
if ($response_code != '1') {
$messageStack->add_session('checkout_payment', $response_msg_to_customer . ' - ' . MODULE_PAYMENT_AUTHORIZENET_AIM_TEXT_DECLINED_MESSAGE, 'error');
zen_redirect(zen_href_link(FILENAME_CHECKOUT_PAYMENT, '', 'SSL', true, false));
}
if (MODULE_PAYMENT_AUTHORIZENET_AIM_AUTHORIZATION_TYPE == 'Authorize') $this->order_status = 1;
}
/**
* Post-process activities. Updates the order-status history data with the auth code from the transaction.
And then set the Completed Order Status to Processing[2].
Thus when an order is placed it'll be forced to 1 (by the code change) and when you capture manually it'll be set to 2 (based on your selection from the pulldown in the module settings) for the Completed Order.