SOLUTION is clearer instructions for Keyboard Modifier than Apple provides. Here it is:
Altering Mappings
You can reinstate your "Control" key as the primary source of keyboard shortcuts using the Modifier Keys menu. To access this menu, click the Apple logo on the toolbar and open "System Preferences." From here, click "Keyboard," then click the "Modifier Keys" button on the following window. To switch the function of your "Command" and "Control" keys, select “Command” from the Control drop-down menu, and “Control” from the Command drop-down menu.
Key Names
In addition to the altered role of the "Command" key, Apple refers to some standard keys by different names. This could cause confusion for users who are not familiar with Apple's terminology. For example, the "Alt" key is usually referred to in OS X circles as the "Option" key. However, it is still fundamentally the same key, with identical locations and functions on both Windows and OS X systems. The same is true for the "Backspace" key, which is known as "Delete" in OS X.
FROM: https://smallbusiness.chron.com/control-key-doesnt-work-microsoft-keyboard-mac-70750.html