How do I change contacts from personal folders to Mailbox on exchange?

[MJ]

Hello;
one of my users contacts does not show the contacts from
the Exchange folders on my server all his contacts are
there but, when he chooses new email and clicks "to" and
chooses contacts there's nothing in there. if you look
at the properties of contacts from the address
book\options and highlight contacts then go to properties
it says it is "personal folders" everyone elses
is "mailbox first name,last name" How do I change it to
that?
thanks!