How to use bash as default shell
brew install bash
sudo nano /etc/shells

# add to last line
/usr/local/bin/bash

# save and quit via kntrl + x


Now, you need to see something like this:

cat /etc/shells

# List of acceptable shells for chpass(1).
# Ftpd will not allow users to connect who are not using
# one of these shells.

/bin/bash
/bin/csh
/bin/ksh
/bin/sh
/bin/tcsh
/bin/zsh
/usr/local/bin/bash  # we added this!


Now set your default shell:

chsh -s /usr/local/bin/bash $USER # this will set for the current user.


Now quit Terminal and re-open it! Check if all ok?

echo $BASH_VERSION # 4.3.42(1)-release