It's a basic but effective fix for a variety of software issues that cause the iPhone to behave strangely at times. On the iPhone, a forced restart works similarly to a soft reset or ordinary reboot without impacting any of your important data saved on the internal memory. Here's how to force a reset on your new iPhone:

• Quickly press and release the Volume Up button.
• Quickly press and release the Volume Down button.
• Then, until the Apple logo shows, press and hold the Side or Power button.