Turn on or off profile prompt
When multiple profiles exist, you can configure Microsoft Outlook 2010 to prompt you when Outlook starts to choose which profile to use. If the profile prompt is turned off, the default profile is used.
In Control Panel, click or double-click Mail.
Where is Mail in Control Panel?
Mail appears in different Control Panel locations depending upon the version of the Microsoft Windows operating system, Control Panel view selected, and whether a 32- or 64-bit operating system or version of Outlook 2010 is installed.
The easiest way to locate Mail is to open Control Panel in Windows, and then in the Search box at the top of the window, type Mail. In Control Panel for Windows XP, type Mail in the Address box.
Click Show Profiles.
Under When starting Microsoft Outlook, use this profile, click Prompt for a profile to be used or Always use this profile.
When Outlook starts, click the profile that you want to use in the Profile Name list.
Set a default profile
In the Choose Profile dialog box, in the Profile Name list, click the profile that you want to be the default.
Click Options, and then, under Options, select the Set as default profile check box.