You can't edit them in the form view during runtime or in the data source taskpane at design time?
I'm guessing the latter which is by design. You can change the editability, but InfoPath by default assumes that imported schemas (in this case the Web Services) are read-only. That's because editing could break the query since the schema "owner" is the Web Service not the receive connection in InfoPath. You can File->Save As Source Files and edit the manifest.xsf to change Editability to Full for the web service schema which will let you edit.
Hope that helps!