If you change all of your items to Walmart Only, but have certain items that are fulfilled by 3rd party merchants, then you can either edit those particular entries in Sku Grid and change the drop down that says Walmart Only to All Sellers. Click Update Item. Then do a Recheck ASAP and Force Reprice of the item. Or you can do it for selected items, by putting a check mark next to them, click Multi Item Actions --> Update Store Options --> Walmart --> All Sellers. Then do Multi Item Actions --> Recheck Selected Items ASAP and Multi Item Actions --> Force Update Selected Items.