Why aren't my changes to a .pdf not saving?

I am running Acrobat Pro 9 for Mac (9.5.4).  I received an unlocked, not signed .pdf brocure.  I made some edits (rotating pages, inserting arrow and comments, etc), "save[d] As" giving it a new name, and closed the file.  Later, I re-opened it, and none of the rotational changes I made had been saved, and a few of the aded/typed comments were either reformatted so as to be unreadable, or were otherwise misplaced.  What am I doing wrong?  Thanks