Press Alt + F11, in the left project pane find your workbook, double click
ThisWorkbook and paste the below
Private Sub Workbook_BeforeSave(ByVal SaveAsUI As Boolean, Cancel As
Boolean)
Worksheets("Sheet1").Range("A1").Value = Now()
End Sub
press Alt + Q to close the VBE, save and close and restart excel. From now
on every time you (somebody)
save the workbook that particular date and time will show in A1 in Sheet1,
if the name of your worksheet
differs just replace "Sheet1" with the name of your worksheet and replace
"A1" with the cell where you want this.