Copyin multiple sheets data into one line
 

I have 4 sheets that each have an approval line. I want to copy that text
into one approval summary line on another sheet. As soon as I add text to
any sheet other than the first sheet I get the error #VALUE. Is there any
way to write a formula that will accept each addition of text and overwrite
the previous text?

Example:
1st update 2nd update 3rd update 4th update
Changes /update
Sheet 1 Sheet 2 Sheet 3 Sheet 4
Summary Sheet
Mario R Mario J Ramos Mario Ramos Mario J Ramos Mario J
Ramos

I would first want to pick up Mario R. Then with the next update I would
want it to change to Mario J Ramos. The next update the summary sheet should
read Mario Ramos. And then with the last update I would like it to take the
last data entered, Mario J Ramos.
Also, can I assign password protection to these individual cells without
protecting the entire worksheet?
Thank-you so much,
--
MT