EW will fit in whatever your screen size is in windows. If it's going off the screen then you may need to adjust the projector so that it fits your screen properly.

If you close EW, you should see your desktop background on the screen. Does it go off the screen also? If so, you will need to adjust the settings of your projector. If not, then you need to make sure EW is set in the Options to display on your Secondary monitor and not on a Custom Position.