If you have entered them as dates like 11/1, 11/2 etc.

Open Find and replace and
replace 11/1 with 12/1 for all matches after choosing workbook in the
'within' drop box

If you have entered as Text then find and replace Nov with Dec.

"Midwest Farmers" wrote:

I have a 5 page worksheet. Each page has approx. 50 customer name headings .
Each customer has a list of dates vertically, Nov-1 through Nov-30, for
example. Information is entered on each day. I need to change Nov to Dec
throughout not only the entire 50 customers on that page but all the other 4
pages as well. How do I do that?