Mac Mail 16.0 new mail and preferences windows size issue

I was trying to create a new Signature for an account that I had to delete and recreate.

Suddenly, the size of the Preferences window changed to be 2x the width of my screen.

The height of the window did not change.

I have to slide scroll the window to go from one side to the other.

There is NO green button to resize the window and there are no Resize arrows shown when I move the mouse cursor to the edge of the window. I have attached a screenshot of what the Preferences window looks like now.

I deleted the new Signatures I created, but the window size is still too big, even after rebooting my MacBookPro.

I later noticed that a Compose New Message window is also stretched to be about 2x the width of my screen, but there is a green button that changes the window to fit the screen, in Full Screen mode, with the text on the left side of the window. If I click on the green button again, the window returns to the 2x stretched version.

I am running macOS Monterey 12.7.4 and the Mac Mail version is 16.0

Where can I find a Preferences file, that might contain settings to change the new default size of this window ?

Thanks for any suggestions.