1) Click on 'Manage Inventory' under the 'Inventory' heading of the Control Panel.
2) Search for your item by it's 'Item ID' (or Author / Title by clicking on filter icon)
Click on the filter icon to open advanced search filters.
It opens a sliding modal where you can search an item such as by Author/Title, etc.
5) On this page you can edit an individual item's eBay properties. You can update your Pricing, Best Offer, Category & Listing properties. from eBay. As you scroll down you can edit your item's Shipping, Return & Payment Policies as well as your Package, Stock & 'Quantity Per Buyer' properties.
6) When you are finished editing your item's eBay properties, be sure to click the 'Save' button to finalize.