First, you never add data to the address book view. You add them to your
Contacts Folder.
Second, clarify what data you are entering, where, and which field you think
Outlook is changing that it shouldn't. Specify your Outlook version.
The Email Display As field is populated automatically by Outlook. You cannot
specify which format Outlook uses. You can only change it after the fact if
you think there is some reason to. There never is. I suspect Outlook is
behaving as designed.