Re: I change the image size in psd but when i print the change does not take effect. why?

I would bet that your not doing it correctly.  Some screen capture would be helpful.  The First question I would have  is: Does your image have a 2:3 aspect ratio? This is required. If you wish to print a 4"x by 6" portrait.   4x6 is a 2:3 aspect ratio.