Multiple Standard User Accounts & APP Access Issues

Hi .... I am having inconsistences with setting up multiple user accounts so they can access only certain applications. For example User1 can see only APP "A" and "B", User2 can see only App "C". This works usually if when I install a new APP when logged in as specific User. However I have a situation where APPS have already been installed and they are viewable/accessible across both User1 and User2. So I go in via control panel and uninstall the specific app and re-install it on User1 only. When I check both users can still see and access the APP. I am not sure what I have done wrong, or I just do not understand how this should work ?


Any ideas or feedback is greatly appreciated.

Thanks