How to configure Default Carrier Settings:
To set a default carrier go to 'Settings' >'Integrations'. Near the middle of the screen you will see an option for 'Default Domestic Courier' and 'Default International Courier'. Both of these options will have a drop-down menu which will be populated by all the Couriers that you have integrated with your account.
Choose the appropriate Courier from the drop-down list and click 'Save' to apply it to any orders that you import according to the delivery address.