How can i change registration info?

I wrote to Yahoo with the following question "I'm not from US or Canada, why can't i use Thunderbird?"
They answered "Because your Yahoo! Account has accepted a U.S. terms of service, unfortunately, POP and Forwarding (and therefore POP functionality with Thunderbird) are only available within your account when you sign-up for a Mail Plus subscription."

My question to you guys is if it's possible to change my terms of service to what it really it is?

 

I think that it would be better to create a new account...

 

That's the problem - thats my main an oldest email and i can't merge accounts with Yahoo plus. But i think i might not have a choice...