Careful 'bout that.  In FF7, it's just better to leave the controller
settings to their default.  It takes a little getting used to, but if
you change them to something else, then sometimes the buttons don't do
what you expect.  The game will tell you to use one button, but you
actually have to use a different one.  In other parts of the game, the
controller settings revert to the default settings temporarily, and
leave you high and dry.

I did it once.  I'll never do it again.  It takes about ten minutes to
get used to the default settings.

Now if I could just find a way to get Cloud to run by default so I
don't have to hold down the O button all the time.