Touch input from external monitor is recognized on the wrong screen

I have an external monitor that supports touch input. It's connected through HDMI and USB to my new MacBook Pro. When I touch the screen, the input is executed on the main display (so the internal one) instead of on the touchscreen itself (the external one). I had a similar problem with my Windows laptop, but there is a setting for which screen the touch input is executed on. I couldn't find anything similar for Mac. Anybody got any tips?