If PC COE is used to manage the proxy settings in your computer, then even if you change it manually, the software will change it back because of the way it's configured. I recommend checking the manuals for the application. There is one PDF which provides all the necessary details in a very detailed mode.
You can download it through the Google Search website: https://goo.gl/gIq87b
Note: Search for HarmonyInformation website where the PDF is stored.