Hey Scottshep,
Thanks for writing in to the forum. This is actually expected! For our plugin, the widget area is moreso intended to be used to drag where you want your sign up form to be in your layout. To make changes to your plugin’s settings (like what MailChimp account it’s tied to), you’ll want to make changes from the plugin settings area, rather than the widget area.
To do this, login to your WordPress Admin area, then go to Plugins > Installed Plugins. From there, go to the MailChimp plugin and click settings. You should then be prompted to set up your account with the plugin, designate which list to connect with, as well as a few other options!
If you have any questions, just let us know. 🙂