How can you add a bind command to bash, so that it automatically happens every session

I want to change bash's default behavior, so that the up and down keys use search-history-forward(and back), instead of previous and next history. Got the idea from this thread. Pretty sure I just need to add:

bind '"\e[A": history-search-backward'

bind '"\e[B": history-search-forward'

to some bash file, but can't figure out which one. Thanks.