I use this code below to prevent a PPT from scrolling to certain slides. However, it disrupts all other open PPTs. How to make it PPT specific?

Sub OnSlideShowPageChange()    
Dim oPres As Presentation
Set oPres = ActivePresentation
With oPres.SlideShowSettings
      .LoopUntilStopped = msoCTrue
      .AdvanceMode = ppSlideShowUseSlideTimings
      .ShowType = ppShowTypeWindow
End With
Select Case oPres.SlideShowWindow.View.CurrentShowPosition
'might be more flexible
Case 1, 3, 4, 6, 8, 17
With SlideShowWindows(1).View
     .GotoSlide (.LastSlideViewed.slideIndex), msoFalse
End With
Case Else
    Exit Sub
End Select
End Sub