BA was mistakenly deployed with wrong currency. How to change it?
It is not possible to change the default system currency, an installation is to be redeployed. This is explained by the system internal actions made when you setup a default currency - it is set in lots of database tables and there is no easy way to find all of them and redefine the currency there. There is a feature request with id #PBA-39271 to implement such operation possibility.