The only way to do a date stamp so that it does not change when the sheet recalculates is to manual enter the deatails in the required cell or with a Worksheet change event macro.

To build a macro you will need to supply details of what rows or columns or range of cells the macro needs to monitor. Where does the macro put the date stamp .

Example Worksheet change macro
you change entry in any columns from a to e the date stamp goes into column f of the same row.

To install macro to correct location

Copy this macro
GoTo Excel
Select sheet this is to appy to
Right Click on Sheet Name Tab > select View Code
Past macro into the Worksheet Module displayed
Return to Excel & try entering data into any cell in column a to e

Private Sub Worksheet_Change(ByVal Target As Range)
   Dim Rng As Range

   For Each Rng In Target
      Select Case Rng.Column
      Case 1 To 5
         Application.EnableEvents = False
         Cells(Rng.Row, "f").Value = Now()
      End Select
   Next Rng
   Application.EnableEvents = True
End Sub