the request for the forum came from my computer, and the message of authentification came from IP 62 35 236 153 which is not my IP, How to change it?

Opera gives an IP adress for me in the US, but I am in France!! so some sites do not accept my opera seen as Spam. Video sites tell me they do not send streaming to my IP adress. I tried Firefox and there was no problem. How do I change the IP adress Opera 30 gives to the prober one? At the moment it gives a 185. adress whereas France I have 192. adress