In case, you performed export operations before and saved configurations, you can make some modifications in the listing.
In the "Edit" form you can see some positions in green - these are the items which have been exported on eBay before and have the eBay ID.
Use the top options to perform the following operations with the existing listing:
[Add Products] - upload new items to the listing from selected categories. Check the Category(ies) that you want to upload items from to add them to the new Listing
[Remove Selected] - highlighted products will be removed from a listing.
Note: to restore a list of products that just have been removed or modified, click the [Back] button and confirm the following action in the pop-up notification:
When you exit the "Edit" form, the content of the listing will be restored before modifications.
If the listing has positions in red, these items are removed from a store and will not be processed during export. You can delete them by using the [Clear Missing] button.