Cell as a button

rbalza 

Right-click the sheet tab.

Select 'View Code' from the context menu.

I created a Worksheet_BeforeDoubleClick event procedure. This is run automatically each time you double-click a cell.

Private Sub Worksheet_BeforeDoubleClick(ByVal Target As Range, Cancel As Boolean)
    If Not Intersect(Range("B2:B20"), Target) Is Nothing Then
        Cancel = True
        Select Case Target.Value
            Case "X"
                Target.Value = "P"
            Case "O"
                Target.Value = "X"
            Case Else
                Target.Value = "O"
        End Select
    End If
End Sub

The code first checks whether the cell is in the range B2:B20.

If so, it sets Cancel to True to prevent going into edit mode.

Then it changes the value of the cell depending on the current value.