1. Select all the cells that contain the formulas you want to change.
2. Go to the formula bar and edit the formula to reflect the correct calculations based on the new workbook. For example, if the original formula was
   Formula:

   =SUM([Workbook1]Sheet1!A1:A10) 

   , and you want to change it to
   Formula:

   =SUM([Workbook2]Sheet1!A1:A10) 

   , you would simply replace "Workbook1" with "Workbook2".
3. Press the Ctrl + Enter keys on your keyboard.
4. Check that the new formula has been applied correctly to all the cells.

By following these steps, you can change the formula for multiple cells at once, saving you a lot of time and effort.