Problem: LyX 2.0.5.1, LyX Tutorial, Section 2.1.1, foot 3 = "You can save time .."

[Gordon Watson]

I read this, from foot 3 (footnote 3): "You can save time by leaving the 
PDF-viewer running in the background. Then, you can use View->Update or the 
toolbar button [X]  and just click on the PDF-viewer window (or unminimize it) 
afterwards."

I'm using Adobe Reader 9 (Version 9.5.3) to generate my PDFs. But I must CLOSE 
a PDF if I want to see the next (updated) version.

So, in short: "View->Update or the toolbar button [X] " do not work for me.

So, is LyX Tutorial wrong; or is my LyX setup the problem?

Thanks.