Private Sub Worksheet_Change(ByVal Target As Range)
Dim A As Range, B As Range, j As Range, lr As Long
lr = Cells.Find("*", , xlValues, , xlRows, xlPrevious).Row
Application.ScreenUpdating = False
Set A = Range("R2:R" & lr)
Set B = Range("D2:F" & lr)
For Each j In Union(A, B)
With j
'Modify it to suit you
'.NumberFormat = "mm/dd/yyyy"
.NumberFormat = "yyyy/dd/mm"
End With
Next j
Application.ScreenUpdating = True
End Sub