When you add a new user, all software installed in standard locations is automatically available, you have no choice over what is shared.... so firefox, openoffice and whatever other software you have installed will be available.
If it's Windows you're talking about then that is wrong.
Whether a new user sees the installed software or not depends on whether the software was originally installed "for all users" or "just for me". Any decent installer gives the user that choice. It's possible that firefox and openoffice in particular have craply written installers and don't give that choice, but your "whatever other software" is definitely completely wrong.