Need to change passcode to numeric

Refer to: Use a passcode with your iPhone, iPad, or iPod touch - Apple Support

See the section: If an alert says to change your passcode or you can't adjust your passcode settings

Any luck with changing the passcode? The attached answer isn’t helpful as I know where to change it but it just keeps saying “this password can be easily guessed- change passcode”. And just repeats it over and over as I I have to make it so complicated and long I can’t remember jt. It’s my phone- why can’t I set it to what I want.