for iOS 9.1 software

the iTunes Store, tap , then tap Add to Wish List. To view your Wish
List, tap , then tap Wish List.
Pick your favorite buttons To rearrange the buttons, tap More, then tap
Edit. To replace an icon, drag another icon over the one you want to
replace. Then tap Done.
Purchase, rent, or redeem
Tap an items price (or tap Free), then tap again to buy it. If you see
instead of a price, you’ve already purchased the item and you can
download it again without a charge.
Approve purchases with Family Sharing. With Family Sharing set up,
the family organizer can review and approve purchases made by family
members under a certain age. For more information, see .Family Sharing