You can change your GUID in the player.txt file in your Combat Arms Profiles folder. Mine is like this: EF8C****-7C**-****-****-********** without the stars. Why would you need to know your GUID? If they catch you hacking they can Ban you using your GUID. What is a GUID? It's the ID that you connect to the game with. How can I change or manipulate my GUID? By using this file, but be careful and save your old GUID because if you screw up you might lose it forever. Don't post your GUID here, someone can take it and use it or even report it.