...
- In Outlook select the File menu, click the Account Settings submenu and select "Account Settings..." from that.
- In the Account Settings window make sure your account is selected (it will probably be the only one available) and click the "Change..." button.
- In the Change Account window click the "More Settings..." button.
- In the Microsoft Exchange window on the General tab enter whatever display name you prefer into the "Exchange Account" text box. Then click OK. The change should be immediatetake effect immediately.