Adobe Digital Edition 3.0

When a pdf is opened in this software sometimes the print size is too small. I am wondering when I enlarge it I would like to keep a copy of the book in that size print. There are two options of how to put it into one's library. Will it keep the book in the size you enlarge the print to or is there another way I can enlarge the print and save that book in the enlarged print size?  The reason I ask is I would like to transfer the book in this format to my Barnes and Noble Nook because once a pdf book is put onto the nook library the format can not be enlarged.  Thanks for any help.