I double checked and this did not make a difference. I am using Win10 and regardless of which of my two displays is set to the “Make this my main display”, the Tobii calibration screen always appears on the same monitor. It seems to be more concerned about how the displays are physically connected (which I can’t change), then this software setting. BUT this was not the case earlier! I recently upgraded my windows 10 to the very latest version 1607 Build 14393.10. So, maybe there’s a bug here.