Hi Val,
In order to change your eBay email address in Auctiva, please generate a new token at Auctiva -> My Account(Tab) -> Ebay Settings, by clicking the "Get New Token" link.
We are currently experiencing some technical difficulties with our support site at this time, which is why you received the "Page Cannot Be Displayed" message. However, if you post your Auctiva username to this thread, I will look into this issue for you.
-Mike