If you have a Touch ID set up on your iPhone 6, but you’ll still need a passcode to keep your iPhone safe. If you have an older iPhone without Touch ID, and your device isn’t recognizing your fingerprint for any reason, you’ll need to fall back on a passcode.
If you want to make your passcode even more safe and secure, try a code with special character instead of a simple number passcode.
Follow the below mentioned steps.
Step 1: Swipe and unlock your iPhone, Go to Settings. Tap on Touch ID & Passcode.
Step 2: Enter a 4 digit passcode to the further settings.
Step 3: Turn off the ‘Simple Passcode’ of your iPhone.
Step 4: Again verify your 4 digit passcode and you’ll see the more secure and safe Password in iPhone.