: Not possible via iTunes as the firmware is no longer signed.
Downgrading from iOS 9.3.5 to iOS 8.4.1 is not for the faint of heart. It requires navigating command lines, jailbreaking, and understanding the intricacies of iOS firmware. However, for owners of the iPad 2 or iPhone 4S, the reward is significant. iOS 8.4.1 offers a vastly superior user experience on these legacy devices, transforming them from frustratingly slow devices into usable, snappy tablets for media consumption or light tasks. downgrade ios 9.3.5 to ios 8.4.1
If you just want a faster, more stable experience on an old device, staying on 9.3.5 (or using a lightweight jailbreak) is often better than going back to 8.4.1. : Not possible via iTunes as the firmware