Defaults make future listing creation easier by setting default listing values, but you can still easily editable for individual or groups of products later.
Here is how you can set your default values for Walmart.
Open marketplace connect > Settings > Update Walmart defaults
Price
‘Web Price’ creates a live sync to your store prices (change a price in Shopify and marketplace listings get updated automatically) but you can also choose a constant value (no live sync), % or $ increase/decrease (relative to your web price with live sync) and apply rounding if desired.
Quantity
'Stock Level’ creates a live sync to your Shopify inventory (which gets automatically reduced after sales on marketplaces) but you can also choose a fixed value (no live sync), a buffer (e.g. choosing a buffer of 2 when your store inventory is 5 will display 3 on listings) and max quantity (e.g. choosing a max quantity of 5 will always show 5 on listings unless store inventory drops below 5 where it will show the actual inventory).
Shipping
Set the default Shipping Template ID and Fulfillment Center ID for new products synced with Marketplace Connect.
Auto-list
Choose if new products added to your online store should be automatically listed on Walmart with your chosen default settings (make sure you are happy with all your default settings prior to enabling this!)
For further assistance please reach out to marketplace-connect@shopify.com