Cannot edit formulas in data entry form due to design.
Cause:
This is by design of Microsoft Excel.
Solution:
Edit formulas in the worksheet.
1) Select the cell containing the formula to edit.
2) Do one of the following:
a) Modify the formula in the formula bar.
b) Modify the formula in the cell:
1] Press F2. (The formula appears in the cell.)
2] Modify the formula.
3) Press ENTER.