Page Layout ⇒ Setting margins for document class

[luc4]

Hi! I have to bind my thesis, but I see that, when I set my document to two-sided document, the column is moved so that the inner margin is very small. I would like to keep the same exact margins (I don't know what they are by default) but move the central column of some cm to the outer margin. Is this possible without having to set all the other margins as well?
Thanks!

Luca

[josephwright]

Use the geometry package.

[luc4]

I tried that, using hmargin={47mm,47mm}, but it seems the fancyheader is not correctly resized... not the same size of the column... any idea why?
Thanks!