How to change incorrect Wi-Fi password?

Solution 1:

There are two ways to do this...

Modify the Password in Keychain

You can do this under Keychain Access. You will find all your saved Wi-Fi networks under the "System" keychain in the "Passwords" category.

Double clicking on the SSID (mine are redacted for security) will bring up a dialog box with the details for that particular Wi-Fi network. From here, you can enter in a new password.

Delete the Network & Rejoin

You can also solve the issue by deleteing the network and rejoining it. Simply go into your System Preferences > Network and select your Wi-Fi Adapter. Click on the Advanced... button and you will be able to delete your Wi-Fi Network. Just rejoin and enter in the good password.