How do I change my currency format?
Prices are displayed using a default format for each currency. This default is derived from the core Commerce module itself, meaning we had to hardcode the appearance of the currency symbol along with other aspects of the number format. We could only do this for currencies whose formats we were sure of, so there are plenty that still retain the generic format:
The first thing to do if you find that your prices aren't formatted properly for your currency is to check the issue queue for an existing issue for your currency. If one exists, comment on that issue if it is still unresolved instead of opening a second one. Otherwise, create a new issue providing the proper currency format.
Changing the format is a trivial fix that should be done in seconds. Upon the next release of the module, your currency will be included. We'll respond with a patch for your particular currency when we commit the fix that you can use in the meantime.
We understand, however, that not every currency has a single representative format. This is especially true for multi-national currencies like the Euro, but even within a single country prices may be displayed differently. At this point, your only recourse is to interact with the currency formatting system at the API level, but there is an open issue requesting support for currency format customization through the user interface. When such a module is developed and released, we will link to it through this FAQ page.
And how/where to define the currency(ies)?
Basic currency setup is at
Basic currency setup is at admin/commerce/config/currency - many, many currencies are defined.
The above issue has now been resolved, but as it doesn't look like I have permission to edit this page, I'll state the options here.