Firefox :: How can I make Firefox remember my proxy's username and password?

How can I make Firefox remember my proxy's username and password?
1. Browse to about:config in Firefox
2. Click on "I'll be carefull, I promise!"

3. Search signon.autologin.proxy and network.websocket.enabled in the Search Input Box then change their values as follow:

signon.autologin.proxy=true
network.websocket.enabled=false

4. Restart Firefox, input user name and password for your proxy and click Remember.

https://superuser.com/questions/379160/how-can-i-make-firefox-remember-my-proxys-username-and-password