Tearing my hair out.

I've got three accounts set up: 1 as administrator, one as standard and
one guest.

UAC is on for all of them. I've been trying to install some software to
the standard account ONLY. I've tried from the standard account and from
administrator. I only want that software on the standard account NOT on
the admin.

How do I do that????

Similarly there is software that I use that I only want showing up in
the Admin account NOT on the standard one.

Is there some deep config thing I need to do? Also, is there a way I
can keep UAC on for the standard and guest but NOT for admin?

Please help, I'm at my wits end.....