If this is the same issue it this appears to be a bug (or at least an omission in functionality) - I'd suggest you post a bug at http://issues.ez.no/
@Robin what @Sander has detailed is how to set Subjects in templates that are used to generate emails in the system (information collectors). It's not a general setting but something that is specific to some modules.
There are some details here: http://www.ez.no/developer/articles/how_to_create_ez_publish_forms/form_template_creation_and_modification/(offset)/20