I use an iMac with System OSX 10.6, and have Adobe Reader installed. Today I scanned some documents into my computer using my HP Photosmart All-in-One Printer, Scanner, Copier. When I open the scanned pdf documents, they are huge--300% of normal size. I am able to reduce the size using the +/- button, every time I close them and open them again, they open at the large size. Is there a setting I can change in Adobe Reader or Preferences such that files will open at regular 100% size? Apple Tech Support was able to help me do this by setting my computer to open pdf documents using Apple's Preview application, but there must also be a way to do it using Adobe Reader?
Go to Reader preferences>Page Display>Default layout and zoom>Zoom and set it for what you want.
I was having the same problem and your reply helped me. Thank you very much!