Password
When you select the option to change your password, you will be
  presented with a screen with three fields. The first field is
  asking for your current (old) password -- the one with which
  you logged in with for the current session. The next field is
  for the new password -- what you want the password changed to.
  The third field is a repeat of the second field -- you must
  enter the new password here a second time. Since the password
  is not displayed as you type it, forcing you to type it twice
  helps to insure that you entered it correctly, and helps
  prevent you from being locked out of your account due to a
  typing mistake. Once you have filled in all three forms, press
  the button to submit the password change request. You will then
  be told if the password change was successful or not.
After you change your password, Horde groupware functions will no
  longer work. You will need to log out, then log
  in again, to resume using the Horde groupware apps;.
Note that this changes your physics unix login password.
  Also note that while this password change is immediate on the
  mail server, there may sometimes be a slight delay before it is
  effective on the unix machines for login purposes. If you are
  having problems logging into a unix machine with the new
  password immediately after changing your password, try using
  your old password.