Refresh rate

I am a little confused on the refresh rate. In the CP there is this "Main Window Refresh Rate" and I have it set to 5 (5 seconds?). The refresh rate does not change every 5 seconds unless I actually change it in the user admin where it defaults to 60 seconds where then I can change to 5 seconds for each user.

How can I default it to 5 seconds for every user?

Thanks