Turn on or off profile prompt
When multiple profiles exist, you can configure Outlook to prompt you when it 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 on the version of the Microsoft Windows operating system, the Control Panel view selected, and whether a 32- or 64-bit operating system or version of Outlook 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.
Note The Mail icon appears after Outlook starts for the first time.
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.