Somehow its thinking its still on the 2nd screen but you don't want to have to go back to your desk and plug everything back in to then move the subset editor back to the original single screen.
One quick way to get round it is to edit your tm1p.ini file but a quicker way that doesn't involve shutting down Excel is to press:
- ALT with Space Bar
- Then press M (which is the shortcut for Move)
- Then use your cursor keys to bring the subset editor back to your screen