You probably are even less interested in adding your credit card, but if you want, there's a "Payment Information" section if you click on the "Account" button

You probably are even less interested in adding your credit card, but if you want, there's a "Payment Information" section if you click on the "Account" button dropdown by your apple id in iTunes. I just changed my password to one more unique (I was reusing it elsewhere), and finding the place to do so was surprisingly hard to find (IMO, it's harder than adding payment information).