We have accessed this from the UK, I ended it after the free trial as there were far too many US currency questions which do not make any sense to my child (nor me to be honest). However, we gave it another try as my son really enjoyed the format and kept asking me to let him play. He is autistic and doesn't enjoy school or learning in the usual manner so I subscribed to the Maths again.
The only way I have found to override the currency is to manually select the lessons - but if it keeps him occupied for a bit whilst he isn't in school I'm willing to do this.