OK.
What is "probably" happening is you have a digital camera.
Your digital camera takes a picture using what is called a 4:3 (or 4/3)
aspect ratio. 4 is the width of the picture and 3 is the height of the
picture. The aspect ratio is simply the width/height. So 4/3 = 1.33. If you
look at the dimensions in pixels of your photo file (from your manual) or by
opening Properties of a photo file and you divide the high pixel number by
the low pixel number you will find that the answer will be 1.33.
Now you want to print this and you select a print size. Say 6 x 4. 6 x 4 is
3:2. Divide 6/4 you get 1.5. What you are trying to do is fit 4:3, almost
but not quite a perfect square, into 3:2, a rectangle. This is not going to
fit. (You can't fit perfectly a square peg into a round hole!). So the
software crops a little bit of the top and a little bit of the bottom of
your picture so that your almost square 4:3 will fit into 3:2.
Usually this works fine because we tend to frame a picture with too much sky
above or too much grass below the subject and we do not notice the crop. But
with indoor pictures, we tend to do the opposite and the result is cropping
the heads or feet. Not good.
So what can you do? Instead of letting the software automatically crop for
you, crop it yourself so you can place the crop all at the top, all at the
bottom or any way you want to do it.
The easiest way I know to do this, and it is free is from here:
http://www.faststone.org/
You can crop to any size print you want with this software and print from
there if you want, or save the cropped file and print it with any software
you want.