On a new mac, trying to switch to bash for a minute:

```bash
alex.mills@alex uta-phd %
alex.mills@alex uta-phd % echo $SHELL
/bin/zsh
alex.mills@alex uta-phd %
alex.mills@alex uta-phd % exec bash

The default interactive shell is now zsh.
To update your account to use zsh, please run `chsh -s /bin/zsh`. 
For more details, please visit https://support.apple.com/kb/HT208050.
%na%m %1~ %#
%na%m %1~ %# echo $SHELL
/bin/zsh
%n@%m %1~ %#

```

`echo "$SHELL"` keeps saying I am using `/bin/zsh`

What to do?