I created an extension that changes the date format for OpenCart 184.108.40.206 and 220.127.116.11 to be in U.S. format (01/13/2015). This extension is available for free on the OpenCart Website. This extension doesn’t require you to make any modifications to the code since it uses vQmod. You will need to install vQmod in order for it to work.
You can download it here: http://www.opencart.com/index.php?route=extension/extension/info&token=7c52c980adb2236fd0fc5a5673d4b8f3&extension_id=20949