How to make "fit to width scrolling" default in pdf viewer by vb.net

Question

I have a problem with displaying a PDF file: it tends to display pages individually, and I want it to display pages in a scrolling manner.

I'm just looking for how to enable this feature through code

If File.Exists(PdfFilename) Then
    PDFViewer.LoadFile(PdfFilename)
    PDFViewer.setLayoutMode("")
    PDFViewer.setShowToolbar(True)
    PDFViewer.setZoom(70)
End if