Change the order in which Outlook checks your address lists

If you’re using multiple address books, for example, one for personal use and another for just a hobby-related group, you can change the order in which Outlook checks these address books. This way, when you start writing the name of a contact to the address field of an email, Outlook suggests the most relevant contacts first.

On the Home tab, in the Find group, click Address Book.
Click Tools > Options, and select Custom.
Click the up and down arrows next to the list to move your address books.
Click OK.