One way to go about that is, first, press Ctrl+Tilde key (the one above the Tab key and to the left of the numeral 1 key on most keyboards). That will display all your formulas. Next, select the range whose formulas you want to change. Click on Edit > Replace, type in Region 1 in Find what; and Region 2 or whatever in Replace with, click Replace All and that should do it.
Did you need a macro to do that? Post back if so.