Private Sub Worksheet_BeforeDoubleClick(ByVal Target As Range, Cancel As Boolean)
temp = Array("a", "h", "q", "x")
p = Application.Match(Target, temp, 0)
If Not IsError(p) Then
If p = UBound(temp) + 1 Then p = 0
Else
p = 0
End If
Target = temp(p)
Cancel = True
End Sub