Hi,

You can refer :
http://www.uscellular.com/uscellular/pdf/schlc11-user-manual.pdf

Or
To change the network key (password), open a web browser and type this address: http://mifi.admin/ in the url search bar. This is your mobile hotspot's admin page. If you see a "Welcome"-screen on this page with a "Login password" field, click cancel at the bottom of the page and then "Ok" to cancel the setup wizard. Log in by entering "admin" in the box in the top-right corner and clicking "Login". Click on the "WiFi" link at the top of the screen, this will open the WiFi settings page. You can change the network name (SSID) and network key (password). Click apply to save any changes made. After saving the changes your mobile hotspot will reboot and you will need to select the new wireless network or enter your new network password in order to connect to the mobile hotspot.

Thanks