Pandora, USA and UK IP address

I have a macbook pro running Lion. I use Firefox for 99% of my internet and I have it set up, in the Firefox settings, as the default web browser. I have purchased a subscription to have a UK IP address so I can watch UK shows. I set it up only in Safari because I don't use it much and I noticed when I set it up in Firefox, the speed slowed down a bit.

So, for USA stuff, I use Firefox and for UK stuff, I use Safari, both using different IP addresses.

So, I downloaded Pandora One, which is the desktop application to play music (I am a subscriber) and it is telling me that it is not available in my country. I think because it is somehow using Safari to access the web (the browser that has the UK IP address). I am in the USA, so it is available.

Is there a setting somewhere that I can change so I can change the default browser for the computer to Firefox because I believe there is a setting for the browser for applications that uses Safari.

Thank you

Jessica