I want to change my Apple PASSWORD, not Apple ID how to?

Perhaps to use information such as presented here may help:

•Change your Apple ID password - Apple Support

//support.apple.com/en-us/HT201355

Useful for most things you may need to update, or change;

~ in order to better secure your Apple ID and personal info.

•If you forgot your Apple ID password - Apple Support

//support.apple.com/en-us/HT201487

For the other side, when or if you can't remember clues you

previously had thought to recollect; try & leave a path back.

And too, there's a matter of 'product passcodes' to access.

A Mac's Admin / Standard user accounts also use passwords.