This is an interesting topic to me, Lois, because I play in several different keys (D,G,C,A, Em and some others I probably don't know the name of) without retuning or using a capo.(I do, however, have 1.5 and a 6.5 frets).If other people want to retune or use capos, that's fine, and there will--I'm sure--be exceptions for me here and there. For instance, I use a capo for Reuben's Train. This all comes under the heading of "more than one way to play the dulcimer", I think.
For me, it's just been easier to leave my dulcimer in one tuning (DAd). The majority of the songs I play fall within those 5 keys. As I become more and more familiar with my fretboard, it's easier to try songs in a variety of keys. I do the best in D because that's what I started with, but I'm getting better all the time in switching to , say, G or C.
Until I took music theory classes, I didn't realize that I had always thought of the tunes spatially, or as a series of intervals. To further get the tune down, I thought of the individual notes as having a certain position in a scale (the first note, the fifth note, etc). I now know that these are referred to as "scale degrees" and each degree has its own name--but to keep it simple, they are often referred to by their numbers (with a caret mark " ^ " to show it is a scale degree). I don't know how to type the ^ over the number, however. Anyway, my point is that using scale degrees, "Twinkle, Twinkle Little Star" will always start 1 1 5 5 6 6 5 4 4 3 3 2 2 1, no matter which key you are in. Still, my brain is probably more aware of the long leaps, short hops, and going up or down step-by-step. The numbers just help me be specific in the path I am taking (without having to name the intervals between the notes --and, yes, they all have names, too).
In a way,tab iskind of like using GPS and the car's step-by-step directions for getting somewhere. My brain wants to see the whole map and then know that I will be making several quick turns at the beginning of the trip, then going a long way on the interstate, then making a couple medium length sections and one final turn before arriving at my destination--and then I put numbers on it so I know I go 3 blocks, then turn left and go 2 blocks, then go 138 miles on I-75, etc. The "big picture" stays in my brain and at any given time I know where I am on it.
That's what music is like for me.
So when someone asks me, "How manytunes do you have memorized?!!" it's kind of like asking me how many ways I have memorized of getting from point A to point B in my hometown. I don't get lost trying to find the public library just because I'm starting out at the post office instead of at my house! The "music map" in my brain is even easier to follow, however, because those intervals stay the same no matter what key you're playing in....you just start out in a different spot.
Good luck with your music journey! A big part of enjoying the journey is finding out how you learn and internalize music.
Jan Potts, Lexington, KY
"Use what talents you possess; the woods would be very silent if no birds sang there except those that sang best." Henry Van Dyke