From the web interface:
This can also be changed for multiple lists at the same time if you are subscribed to more than one list on the same domain. See Section 10.1 for information about changing settings globally.
From the email interface:
Commands can appear in either the body or the subject of the message. (See Section 3.2 for more information about sending mail commands.)
If you are not sending mail from your membership address, you can also specify this address with address=ADDRESS after NEWPASSWORD.
For example, if email@example.com wanted to change her mylist password from zirc to miko, but she was sending mail from her work address firstname.lastname@example.org, she could send a message to email@example.com with the subject set to password zirc miko firstname.lastname@example.org.