The command you're referring to is not built into Outlook but must have been added by an add-in. See http://www.outlookcode.com/d/newdefaultform.htm for tools and scripts that should help.

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Sue Mosher, Outlook MVP
Author of Configuring Microsoft Outlook 2003
http://www.turtleflock.com/olconfig/index.htm
and Microsoft Outlook Programming - Jumpstart for
Administrators, Power Users, and Developers
http://www.outlookcode.com/jumpstart.aspx
>I have created a custom contact form and am trying to transfer this form to a
> colleagues computer for use. After sending it to my colleague and opening it
[quoted text clipped - 3 lines]
> drop down menu not offering the option of CHANGE FORM. It shows design form
> or choose form. Can someone please advise how to do this?