Hello Mtcart50,
Please follow the steps provided below:
1) Connect second monitor to Mac;
2) Start Virtual Machine;
3) In the "View" menu from Parallels Desktop check the "Use All Displays in Full Screen" option;
4) Switch the virtual machine into Full screen view mode;
5) Go to Start > Control Panel > Go to Display Settings > Adjust Resolution (on the left pane);
6) Click the additional monitors one-by-one, and in the drop-down menu in the center of the window, select "Extend Windows desktop to this display" for each of the monitors > Click Apply.
7) Restart Windows Virtual Machine and observe Windows in Multiple monitors.
Let us know if you have any additional questions.
