You cannot (are not supposed to be able) to change between E and W. If your RV is registered in the E or C time zone then you should get the NY feed. If your RV is registered in the M or P time zone you should get the LA feed.
The information that you cannot change is correct BUT if you can find the right person you might be able to get both E and W (like those of us who are grandfathered into that service) for an additional $5/month. You just have to call, call again, ask for a supervisor, call again, ask for a supervisor and find someone who will set you up with both coasts.
I pay $20/month and get both E and W coast feeds. There is no reason that you could not either other than the stupid folks put in your way to stop you!