Tom's iPhone 5S died, and he bought a new iPhone 8. But he's not having luck with the 3D touch option. It just doesn't respond. And at other times, it seems overly sensitive. What is going on? Rich says that since the phone is still under warranty, it'll be worth going to the Apple Store and have the digitizer tested. If you don't have one nearby, Best Buy is now an authorized iPhone service center. A reboot of the phone will also help.