April 2020
A year later and EA still has not fixed the issue. People using multiple monitors is pretty common, so why not just incorporate this in development when you make a game like other game developers do? The "accepted" workaround does not work for those who have a different monitor resolution. It simply will not display correctly.
March 2021
So what worked for me was to use steams big picture mode, then go to settings (in big picture mode) go to display, resolution, then change the target monitor. When I opened Apex from big pic mode, after changing that setting it opened on the correct monitor. I hear that you can also open the game in borderless window mode and press 'windows key' + shift + right arrow, or left arrow. I have not tried this myself.