How to Change Auto Lock Time on an iPhone

Open your iPhone's Settings.

Do so by tapping the grey gear icon on one of your Home screens. It might also be in a folder named "Utilities" in your App Library instead.

Scroll down and tap "Display & Brightness."

It's in the third group of settings. This shows your display options.

Tap "Auto-Lock."

You might have to scroll down a little bit to see it.

Review your options.

You can program your phone to automatically lock after any of the following time increments: 30 Seconds 1 Minute 2 Minutes 3 Minutes 4 Minutes 5 Minutes Never

Select your preferred option.

Your phone should now automatically lock after you leave it unlocked and unattended for your chosen amount of time.