Change wifi password (your answer didn't work)

On this thread, https://discussions.apple.com/thread/4131506, user Bimmer 7 Series (I guess that's the user name?) offered this solution for changing your wifi password on a Mac:

"click on your wifi icon - top right - open network prefernces - advance - wifi - look under preferred networks - highlight the network name you want to edit and hit the minus sign.

after you've done that, hit the plus sign search the network you want then fill in the password."

THIS DOES NOT WORK. Upon following these steps multiple times, the "new password" I entered was rejected upon trying to re-connect to the wifi network. PLEASE ADVISE.

Thank you.