ios5.1和6.1之间的UIButton差异

I placed 3 buttons into my view, set up background image and sometimes I need to disable one of them. I find out that they appear different in iOS 5.1 and 6.1. I like the 6.1 version. What should I do to make the design in 5.1 will be the same as in 6.1?I placed 3 buttons into my view, set up backgro