In my main application, I have one group and within that group I am the only one with Administrator level privilege and some others are at manager level and two others are at Data Entry level. In the last tab in the security setting there is application level Security and xuser name and password setting. In the bottom there is checkmark for Allow Everyone or QAgroup (that is the name of my group. If I do not check any box, it automatically put the checkmark in Allow Everyone. If I put Checkmark in QAGroup, it allows everybody in my group to open up my DSR file. What am I doing wrong? I do not want anybody to have access to my designer file. It is really dangerous!!!

Do what Carl says. If the only existing group does not have Designer access, then nobody does, including you. You don't want to completely lock yourself out of your design.