I read a post with the following reply:

As Dave said, you can't "really" make Excel so secure that at competent
person cannot get in, but you "can" make the trip in so confounding that
only a truely dedicated individual will go through all the necessaries to get
there.........thereby, "keeping the honest people out"....
You could incorporate things like: 1-workbook won't open unless macros are
enabled, 2- Pass word(s) are invoked, 3-Only users with name on a list can
access, 4- only user putting secret value into specific cell can gain access,
etc etc........

I will like to know more on the option No. 3 & 4. Can anyone help me on this.
Tnks / r