The auto-lock in iPhone has a sole purpose- to lock screens and put the devices to sleep mode automatically. If you’ve been finding it tough to set or change auto-lock time on your iPhone lock screen settings, here’s a quick fix with this how-to article. Set or Change Auto-Lock Time on iPhone Lock Screen Settings Part 3: Tips: What to Do When You Forget Your iPhone Lock Screen Passcode.Part 2: How to Keep Your Data Safe through iPhone Lock Screen Settings.Part 1: How to Set or Change Auto-Lock Time on iPhone Lock Screen Settings.