language support

Hello dev support , We develop against webex meetings. But now, we have he following questions. 1) we want the teacher who are in U.S. to see the English version. 2) we want the students who are outside U.S to see the Chinese version. In our code, the student will have the roomid, and join as a guest. However, when we open the webex in our webpage, the guest shows the English version even though the O.S and IE are Chinese version. Could you please help us? Thanks a lot. Best Regards,Lingling