Hi A4Photo,
Since each separate eBay site entails a different lister form, it is not currently possible to adjust the "eBay Site" pull-down menu once the listing has been completed, as it sounds like you have already noticed.
Therefore, in order to post a listing you have already created to a different listing site, you would actually have to re-create the listing from scratch beginning with the "NEw Listing" page. If you open up your Auctiva account in two separate browser windows, and paste the information from the completed copy to the new version, it may speed up the process of re-creating these listings.
I hope this information proves useful. If you have any additional questions or concerns, please file a support request using the appropriate link on our help page:
http://www.auctiva.com/free-auction-software-help/help.aspx-Mike