Note: The following is made available under GPL from http://codex.wordpress.org/GPL. It may be edited a little from its original form, but probably not a lot. There is no guarantee this information is accurate…use at your own risk.
To change your password in WordPress v2.7 or later:
1. In the Admin Panel, go to USERS
2. Click on your username in the list to edit
3. In the Edit User screen, scroll down to the New Password section and type in a new password in the two boxes provided. The strength box will show how good (strong) your password is.
4. Click the UPDATE USER button