Each listowner and moderator has their own password to log in to Listbox. To change your password, just click your name in the Welcome greeting at the top right of Home. (You can also search for your own name.) That will take you to your Subscriber page, and you can set your password there.
If you want to change a password for someone else, you will have an option to either resend them their current password, or have us create a new randomly generated password, which we will email them. For security reasons, the existing password will not be displayed.