On the Upload Photo page, there is a section under Appearance on Page labeled as Layout. Next to the slider bar is a box with a number on it followed by px. The number in the box is the pixel size, which for the pictures you want should be set to 64.
Im here to ask if YOU would like to join the DPG wikia. we need new people to help grow this wiki! There is only a few of us working there. Ask me or another ADMIN to find things to fix up and build apon. Thank you!