Is there a way to change all shipping costs at one time instead of doing one at a time?

[wastingtime101]

From your active listings page in seller hub, select all listings and at the top hit the edit button. That will take you to the bulk edit screen @salvia350. 

[threelittlelambs · Accepted solution]

You can also create different shipping cost policies here to choose from when listing or bulk editing:

https://www.bizpolicy.ebay.com/businesspolicy/manage