Right now there is no way to change the Agency currency from the initial currency that was set up. For sub-accounts you have to change the country in the Settings->Company.
There are many reasons why this is not a good idea but the main thing is if you use the short codes to display that information anywhere on sites or use it in funnels, ect. the wrong information/country will display or be used so that is really NOT a solution.
My issue is that I am not located in the US but want the currency for both my Agency account and my sub-account to display in USD as that is the currency I charge in and that is the currency my Stripe and PayPal is set up for.
The request i have is allow us in Settings->Company to choose which currency the account should use. Don't default it from the country selected.