find and replace cell reference to a new worksheet
 

i have 12 sheets in a workbook & each represent a month of the year. There
are multiple formulas that refer to a value on the previous months worksheet.
For each month I need to change the formulas to refer to the previous month.
I have tried to use find and replace to speed up the process but only get a
REF in the cell. The same thing happens if I try to type the new reference
into the formula. The only way I am able to make the formula work is to use =
then go to the cell for the reference and use enter.

Thanks
John