Does it go to the one that the mouse is on at the moment? That seems to be common.
There's also the
xdotool
utility that can do all kinds of things with windows, their placement, mouse and keyboard actions, and more. You'll probably have to install that; I don't think you have it by default.
Here's an excerpt from one of my setup scripts:
Bash:
firefox https://www.youtube.com/live_dashboard?nv=1 &
sleep 5
# Move to other screen
xdotool key ctrl+alt+1 # Works with custom shortcuts (Menu -> [Settings or Favorites] -> System Settings -> Shortcuts -> Shortcuts -> KWin -> Window to Screen X:)
xdotool key ctrl+alt+1 # Again because the first use doesn't work (init bug?)
In this case, my KDE desktop manager can have a keyboard shortcut to natively move a window to a given display, so I set that up and then invoke it here. But
xdotool
might be able to do that as well. Read the (long!) manpage, play with it, and see what you come up with.