FAQ - Frequently Asked Question list - Answer
Question: How to make a new PST file the default file in Outlook?
Answer: You should
- Open Start | Settings | Control Panel | Mail
- Use the Delivery tab to select the corresponding PST file in the Deliver new mail to the following location: combo box and confirm moving the service folders (if necessary).
Thus, the new pst file will be the file used in Outlook by default.