English measurements?

Having trouble getting started. How do I design the room in English (not metric) measurements? Also, even though I chose Lionel O-27 as the track type, it still wants to default to HO-

Thank you; I seem to have been able to get it in "Imperial" measurements. I am still quite frustrated getting started however. I simply want to begin by outlining the 17' x 13' room in which the layout will go. Unfortunately, when I click on "Wall," it immediately starts trying to draw a line which will not "snap" to anything, nor allow me to enter actual dimensions. Thank you for designing this; I hope I am able to use it properly!