Finding the last row

Hello
Good morning!
I was trying to keep a history (in Col. D) of my data entered in a cell (A1)
It is working ok, but started recording from 2nd Row (D2) but I need to start it from the 1st row (D1).
Please help me to correct it. What i need is to keep the track from D1.
Thanks
Toms

Private Sub Worksheet_Change(ByVal Target As Range)

   If Not Intersect(Target, Range("A1")) Is Nothing Then
   confirm = MsgBox("Confirm ?", vbYesNo)
   If confirm = vbYes Then
    
    '    If Range("D65536").End(xlUp).Row = 1 Then
    '    lastrow = 1
    '    Else
 lastrow = Range("D65536").End(xlUp).Row + 1
    '     End If
     Cells(lastrow, 4).Value = Range("A1").Value
      
          End If
   Else
   End If
      
End Sub