LyX ⇒ Page margins are not printed properly.

[Cosm]

I'm trying to set 2 cm top and bottom margins, but it's not working. When I print the pdf created in lyx the margins are larger, about 3 cm. In fact not even the right/left margins come out exactly as I set them (they are printed smaller). Is there a setting I'm missing?

I have tried all the different print scaling settings on my pdf viewer, nothing seems to work, not even the "no scaling" option. I even tried different pdf viewers.

When I measure the margins in my pdf viewer (for example with a 100% zoom) even there the upper and lower margins are not exactly as I set them in lyx. On some pages especially after a footnote the margins can vary a lot.

[Cosm]

I think I found the answer: In document settings "page layout" I changed format to A4 which is the standard printing paper size almost everywhere.