stringing a new dulcimer

Well, the dulcimer is finished and I'm stringing it up this morning. But I have a question about the melody string. For now, I'm just going to have it set up as a 3-string. My nut has all the notches for 3-string, 3+1-string, & 4-string. If I use the outside notch, it looks like the distance between all three strings isn't equal. For just a 3-string set up, which of the two melody string notches should I use, inner or outer?