Hi Heavonlea,
We only automatically generate a scrolling gallery image for each listing once, either when the item is posted or when it is imported into your Auctiva account, so the scrolling gallery image for a listing will not change automatically when you change the header/gallery image in that listing.
If you would like us to update the images in your scrolling gallery to reflect the new images you are using as your header/gallery images, please contact our customer support team and we will be able to do that for you.
If you would prefer to remove the item in question from your scrolling gallery entirely, you can do so by clicking the "Store Items" link under the "Store" tab and marking the item as hidden. If you go that route, the item will then be removed from your scrolling gallery the next time it refreshes, which it does about every 4 hours.
You can contact our customer support team using the web form on the following page of our site:
http://www.auctiva.com/help/requesthelp.aspx-Mike