Go to Setup > Customers.

 Search for the customer that you want to setup the days of service for.

 Click on the edit icon located under the Actions column. This will open the customer details window.

 Click on the Days of Service tab.

 The locations associated to the customer  will appear on the left side of the screen. Select the desired location

 Click on the "Select" located next to the day of the week for which you want to set the "Days of Service".

  The Day of Service window will appear. Click on the carrier's name and click on the "Save" button. The carrier name will appear next to the day of the week.

Repeat the steps above to setup the carrier per location that will be used by default on a given day of the week  

Depending on the location, customer and ship date Komet will suggest the carrier on the following screens: Order Entry, Prebook and E-commerce.