If you have an Outlook Data File and you want to set it as default Outlook Data File means whenever you open Outlook always that PST file should be open, here are some few steps to make it :

Step 1

• Go to File menu, click on Tools.
• Then select Account Settings option.

Step 2

• A window will be open.
• Now go to Data Files tab where you will find all PST which was opened in Outlook. You can select that PST which you want to make default.
• If you want to make a new PST file as default then click on Add, where you can browse an existing PST or you can create a new PST. Now that PST file will be added to this window which is showing below:

Step 3

Now select that appropriate PST file.

Step 4

• Now click on Set as Default. That PST file will be set as default PST file.
• Click on Close.

Now restart the Outlook. The default PST will be changed and you can see that Outlook Data File items in Outlook which you have set as default.