user can't change password

how can I make user can not change the password??

I don't think you can do that.

Why can not, and why are not made

no you can not allow the user not be bale to change there pass words.
email address,user names yes but not pass words.

should be held so that members do not get hacked

Sorry but you can't prevent users from changing their passwords. Its their account and they can do what they want to make it safe.