How to change from 6 digit passcode to 4 digit

Go to Settings/Face ID & Passcode (or Touch ID & Passcode on phones without Face ID), tap Change passcode, enter the 6 digit passcode, then tap Passcode Options and you can select 4 digits. Note that 4 digits is much less secure than 6, so only change it if you have no data on your phone that you don’t mind being stolen.

Try the following:

1. Open Settings
2. Tap Face ID & Passcode
3. Enter your passcode
4. Tap Change Passcode
5. Enter your passcode
6. Tap Passcode Options
7. Tap 4-Digit Numeric Code
8. Enter your new passcode

You should stay with the six number Password. It is much more secure.