Yes, it is the program. The primary window is subservient to all other windows. But here is something you might try. Windows from the 'Tools' menu such as the Flight Strip Bay, Controllers & Chat, etc., can be 'rolled up' like a window shade when not needed for viewing by clicking the header bar on the window. You cannot do this with viewing windows because they will enlarge to full screen when you click the header bar. So Tools windows that you only need to see temporarily for info can be placed on top of the Primary view screen at the top so that the header bar is over the Primary window header bar. While controlling keep them rolled up and only open them long enough to view the information you need to see then roll them back up again when done. This will give you move real estate on your second monitor.
I am emailing you a PDF document I created to help my new controllers in setting up their VRC screen. I hope you find some helpful information in it.