This has been a problem with MS for years, not being able to assign certain apps to open in Monitor 1 or Monitor 2. Generally, the last monitor that an app was closed in will reopen in that monitor. I would suggest moving the app(s) over to the second window after opening them in your primary monitor window and then close them and reopen them to see if they open on monitor 2. This works for me in most apps (but not all). The downside to that is if you shut your PC down, you have to start all over again. It's a PITA.