I have an array of formulas.
I wanted to enable manual user input on these array but
still preserve the formula. So I added a checkbox.
(DefaultOpt).

If the box is checked the formula is restored into the
cells in the array. The following code seems to work. (But
suggestion for any improvement is welcome. I am sort of
green at Excel/VBA)

----
Private Sub defaultOpt_Click()
For i = 15 To 28
ActiveWorkbook.Worksheets("Model 2").Cells(i,
4).Formula = "=FORMULA HERE"
end sub
----

However, I also want to make sure that, if the value of a
cell in the array is changed, the box should become
unchecked.

Any suggestion how I proceed to do this?
Thanks in advance,
pac