My password in Apple ID cannot be changed it is frozen
My Apple ID password does not allow changes
If it was that easy then it wouldn't be secure. I can't change my particular Apple ID either because I bought an iMac and set-up an Apple ID during a specific window of time in 2008 or 2009 when Apple had Mobile Me. But I can still change my password.
Nowadays you kinda have to 'jump through hoops' to:
Apple ID: Changing your password
Or you can Change your Apple ID
Or you can use this list Frequently asked questions about Apple ID
Best Regards,
mm