You can have up to 4 currency accounts (one in USD, one in GBP, one in CHF, one in PLN) if you have Premium membership. 

1. Go to the "Finances" section at the bottom of the main screen in the application. 
2. Click on "Open new account"
3. Select the currency in which you want to create a new account. 
4. Click "Continue". 
5.  Your additional account has been opened.