Sharing Contacts - really need help!

I am sharing contacts between 2 computers and want all
contacts to be able to be seen on both computers.
However the private box is checked on most of the
contacts that I am trying to share.
How do I uncheck the private setting/box on all of them -
other than having to go through and do each one
individually - which would take forever.
Is there a default somewhere that makes it automatically
check the private box? and if so how do i change this.
Thank you in anticipation of some help.
Regards
Danella