While in your spreadsheet, unlock all those cells where you want to allow
users to enter data. (Format, Cells, Protection, untick "Locked").
Now click on Tools, Protection, Protect Sheet. There are a number of
options you can select or deselect. At this stage you can also specify a
password to unprotect the sheet, so that only you can do that. Users can
then copy data from your protected cells, but cannot overwrite it. Check
Excel Help on this

"LCK" wrote:

I have a range of validated cells where the user can only pick values from
the specified list. I don't want them to be able to overwrite these cells
with values not in the list by pasting data etc. How do I prevent this?