Photosmart 5524 eprint from an Ipad - how to manage print size & crop

Hi, very new to this eprint malarkey, got the printer set up and it's printing fine, but how does one manage the final print size and crop? I've wasted a lot of paper and ink trying many different things... There must be an easier way?!?

I have some square photos that I've tried printing... The printer fills them to the a4 page but chops the sides off... I've recreated the image with extra white borders and it's now printing very small! Arrrrrrrgh!!

Any help would be much appreciated!!