How to upgrade my login shell from bash version 3 to 4? Current I am running 

$ echo $BASH_VERSION
$ 3.2.57(1)-release


I have the new shell in

/usr/local/bin/bash


and I can run it directly with

/usr/local/bin/bash
$ echo $BASH_VERSION
$ 4.3.42(1)-release


I have done 

$ chsh -s /usr/local/bin/bash
I needed to fully quit the terminal application in order for the changes to take effect.  osx is different in this way as it leaves applications 'open' even when all current window occurrences of it are closed.