I got super annoyed that it wouldn't actually exit when I exited. The music would keep playing.

Were going to install a plugin to fix that

# install git if you dont already have it
sudo apt-get install git

cd ~/.local/share/rhythmbox/plugins
git clone https://github.com/fossfreedom/close-on-hide

If you are using Rhythmbox v2.99 or earlier open the .plugin file and change the line: "Loader=python3" to "Loader=python"

Related External Links:

• Ask Ubuntu - Is There A Plugin for Rhythmbox to Exit on Close