When changing passwords for accounts in WordPress, it appears that the password doesn’t change. Other mechanisms like forgot password etc don’t seem to fix the issue. Observing changes on the back end, the password does change in the database, the issue appears to be with browser caching and cookies. Some suggestions is to clear cache and cookies from your browser and use /wp-login.php rather than /wp-admin. I have only noticed this on Mac instances and don’t have any concrete way of reproducing this or a work around.