Hi lbjnflower,
Are you referring to eBay categories or your custome eBay store categories?
If you're referring to your custom eBay store categories, please go to Auctiva -> My Account(Tab) -> Ebay Settings, and click the "Update Store Categories" link. Once you have done this, there will be 2 pull down menus on the lister page, directly under the category field, from which you can specify up to 2 custom eBay store categories.
If you are referring to standard eBay categories, I recommend filing a support case using the appropriate link on our help page:
http://www.auctiva.com/free_auction_software_help/help.aspx
-Mike