When creating a bank account you will have to choose what kind of fileformat you are going to use with it. Usually there will only be one to choose.
If there are more than one option, your bank will be able to tell you what fileformat they use in their system, this will most likely be either XML or ISO20022.
When creating a new bank account, you have to add bank account informations.
On the last tab you will have the option to choose the fileformat you want.
When you have chosen, you just have to press "Save" and your bank account has been made.
If you need to change your choice later on, you can follow this guide: Here.