To change the contact in the job, go to the "Contact" tab on the right side while inside the job.
To change the contact, click "Edit."
The drop down menu will appear with all of your contacts saved in the address book and their associated Company contacts.
Click a contact, and press "Save."
If you change the contact information in the address book, it will not automatically change the contact information inside the job. You will need to go the contact tab inside the job and click "Update" for the new information to appear on the documents.