You cannot control security from VBA. If you think about it this is A GOOD
THING!

The user could set their internet security level to low. This is done from IE
in tools, options, security. There are many settings you can adjust and I am
not sure if this is one that can be adjusted individually. The problem  is
that setting it to low does make the computer more vulnerable to virus attack.

If the file  has macros in it, the creator can digitally sign it and install
the certificate on the user's computer. Details of how to do this are on the
website http://www.mousetrax.com/techtrax. I am not sure quite where. There
was a discussion of this recently on, I think, the Word VBA list.