By default:
When a new shift job is input by a client it goes in the "Requested" status
When a shift job is broadcasted it goes into the "Broadcasted" status
When a shift job is assigned to a candidate it goes into the "Assigned" status
To customize these, click on any shift job in the shift job calendar and click on the gear icon next to the status drop down:
Here you will find the ability to change these default statuses with these settings: