If you downloaded iOS 9 on an iPhone 4s, you may be entitled to a refund check

Apple reaches class-action settlement over ‘decreased performance.’

Full Guide on How to Update iPhone 4/4S to iOS 9

Things You Need to do before Installing iOS 9

iPhone 4 - Wikipedia

iPhone Unlocker - Remove Screen Passcode and Apple ID on iPhone, iPad and iPod

Full Guide on How to Update iPhone 4/4S to iOS 9

fluff] 64gb iPhone 4s updated from slow iOS version (7 I think) to faster one given by friend : r/LegacyJailbreak

iPhone 4S For Dummies: 9781118036716: Baig, Edward C., LeVitus, Bob: Books

If you have forgotten your Apple ID password - Apple Support (SG)

9 Ways to Fix iPhone Stuck on Preparing Update to iOS 14

View your purchase history for the App Store and other Apple media services - Apple Support (PH)

How Apple Ruined The iPhone Camera App In iOS 7