Q: Where do I go to change my PayPal email for existing listings in Sku Grid?
A: You would change your PayPal email address for existing listings directly in your eBay account in your business policy management section. You would have to edit your payment profile/policy. This would not be done in Sku Grid.
Now, if you are listing with Sku Fetch, it would depend ultimately on which external lister you're using (file exchange, eBay selling manager, wise lister, ink frog, etc) as you'd need to update your policy information thereafter making changes to your policies on eBay.
If you're not listing with Sku Fetch and one of our listers, then there's definitely wouldn't be anything to do on this end. It would only be directly on eBay.