Excel VBA Range and Values not goin IN?

[Robbo]

Any one help

trying to get this to work can change the fon and cell colour but cant put a value in the CELL
the C B A and AA

everytime have in the code they move it back to the top so only does the first cell P12-Q12

Public Sub Worksheet_Change(ByVal Target As Range)
Set MyTotal = Range("P12:P391")

For Each Cell In MyTotal
        If Cell.Value < 40 Then
            Cell.Offset(0, 1).Interior.ColorIndex = 5 'BLUE
            Cell.Offset(0, 1).Font.ColorIndex = 2 'BLACK
            'cell.Offset(0, 1).Value = "C"
        End If
        If Cell.Value > 40 Then
            Cell.Offset(0, 1).Interior.ColorIndex = 10 'GREEN
            Cell.Offset(0, 1).Font.ColorIndex = 2 'BLACK
            'cell.Offset(0, 1).Value = "B"
        End If
        If Cell.Value > 80 Then
            Cell.Offset(0, 1).Interior.ColorIndex = 6 'YELLOW
            Cell.Offset(0, 1).Font.ColorIndex = 0 'WHITE
            'cell.Offset(0, 1).Value = "A"
        End If
        If Cell.Value > 120 Then
            Cell.Offset(0, 1).Interior.ColorIndex = 3 'RED
            Cell.Offset(0, 1).Font.ColorIndex = 2 'BLACK
           ' cell.Offset(0, 1).Value = "AA"
        End If
        If Cell.Value = 0 Then
            'Cell.Offset(0, 1).Select
            Cell.Offset(0, 1).Interior.ColorIndex = xlNone ' WHITE
            Cell.Offset(0, 1).Font.ColorIndex = 0 'WHITE
        End If
Next
End Sub

any help ?