To change your account settings, you must specify new parameters and password(email of your workers). If you do not want to change some settings, leave fields of these settings blank.
You must use one email for all of your workers.
To be able to change your settings you must use the email optional parameter with every miner you have, and it's value must be the same.
If you are getting "incorrect password" message:
1) Check all the workers use the same email
2) It is populated with every miner you have