Enter the username: admin and the password password (Note: If this doesn't get you in, hold the reset button 30 seconds and it will factory default the unit to admin/password. This will also default the wifi name/password to be what is on the label on the back of the unit)
Once logged in, click on Wireless on the left. You'll see the screen similar to what you see here. Change the Password to your desired password..
Note: We recommend changing the Name (SSID) when changing the password. Some devices will not prompt you for a new password if the password on your WiFi network changes. so you don't have to wade through all the steps to make your computers or devices "forget" the network so you can put a password in.
Click apply at the top of the page, and log into your new network when it shows up. It can take up to 5 minutes for your devices to see the new network names.