Illustrator workspaces automatically adjusting to dual screen / external monitor

Can someone please help me!?

I have a Macbook Pro 13" running Big Sur (11.2.1) as well as an 21" Apple Cinema Display.

I am running Illustrator 2019.

I have my workspace set up with on my laptop with all the Pallettes along one colum on the right and a tool pallete to the left of the work area.

When I plug in my 21" external dispaly I obivously have a lot more room and so I resize the windows and also pull the Layers pallette into it's own colum to see more layers. I move them all onto the external monitor and then use the laptop screen for other applicaitons. 

I believe I have set up both options as New Workspaces (which I call Dual Monitor and Single Monitor).

However when I unplug the external monitor and then select Single Monitor workspace, it doesn't resize the windows, it only moves the pallettes around.  So I am stuck with this extra large set of winodw half of the screen which I then need to carefully select and resize.

Is there a way that the Workspace options can work how I want them to?