Ah,,,,,, ok. So, I've been trying this thing for quite some time now and find that it takes some trial and error. I'm tall but I carry my bags somewhat on the short side - I don't like to droop all the way down to my lower thigh area. Vice versa, some of the shorter dudes carry their stuff a little long. Another variable is the height of the carry on bag. If you are short and the bag also happens to be a 20 inch bag instead of the 22 inch bag, which the pic is based on, you may have easier time matching up with the length of the shoulder strap.

I guess my point is that it's not that hard to find the strap length that works for your short height and the length of the bag so that you don't have to fiddle with adjusting the length of the strap every time you "piggy back" the strap on the carry on.

Good luck.