Changing base currency I set up a new shop and the base currency is US dollars. However I want to change this to Euro's. How can I do this?

In Commerce --> Settings --> Payment Currencies I can add new currencies but I can't set it as the new default.

Am I looking in the wrong spot?
Click on USD under Commerce->Settings->Payment Currencies and change the dropdown from USD to EUR.  That will become Commerce's new base/primary currency.

If you also want to support USD, you can add it as a second currency now and setup a conversion rate.