"request coins" address is different to top right qr code
On the main screen (not the request coins page), you should see a little Tag symbol up the top in the menu bar. That opens up your address book. Swipe over to the 'Your addresses' tab, and you'll see a list of all the addresses generated by the request coins page. You can give each one a label on this page too so you remember what they are for.

The app generates a new address for each payment for privacy reasons.