Bing Rewards

You should set region, in which this app is available and then reboot your phone.
Did you do it this way?
 
don't think so, it's not just an app thing, it's a regional thing for the program, you can't sign up for it, because it'll know based on your IP (I guess) that you're not in the right region. I tried signing up using my computer and it told me it's not available in my region, so has nothing to do with changing regional settings on the phone.
But can I change my region then to UK?