Private Sub Worksheet_Change(ByVal Target As Range)
    Dim rw As Range
    Dim lastRow As Long
    For Each rw In Target.Rows
    If Cells.Item(1, Target.Column).Value = "PROGRAM" And UCase(rw.Value) = "ON" Then
           lastRow = Cells(Rows.Count, Target.Column).End(xlUp).Row
           For i = 2 To lastRow
            If UCase(Cells(i, Target.Column).Value) = "ON" And i <> Target.Row Then
                   Cells(i, Target.Column).Value = "OFF"
            End If
            Next
        End If
    Next
 End Sub