I think if you are using ASME standards, you are pretty much stuck with the double letter. All the examples is ASME shows the views with A-A, B-B, etc.
ISO uses the arrow method to show views and uses a single letter, but doesn't include the word description (section, view, etc), it just say 'A' under the view.
I've never needed to change to an ISO format so I don't know exactly what it takes. I assume there are several switches in the drawing setup file you would need to change.