Following this answer fixed my previous problems/errors, but when I restart my terminal and start a new session the versions of Rails updates from 2.0.2 to 4.0.0 and Ruby updates from 1.8.7 to 1.9.3p448, which then causes my previous errors to appear.
How can I permanently keep the settings from the post so that I don't have to re-enter those 7 commands again?