Okay, everyone wanted a short hair tutorial, so here it is!
You're going to need 2 strands of embroidery floss and 2 pieces of cardboard, one measuring 4x3 inches, and the other one measuring 4x1 inches.
Wrap one whole strand around each piece of cardboard. I'm going to call the small, skinny long piece (on the right) the bottom piece, and the bigger one (on the left) the top piece.
Carefully take the floss off of the cardboard and tape the floss to make sure it won't move too much when you sew it.
Now use a machine to sew between the tape. (You don't need to worry about the color of the thread in the sewing machine too much. I use a brown thread for any hair color that isn't blond, because it doesn't need to exactly match the color of the embroidery floss) For the bottom piece, just sew a line as close to the top as you can. Don't sew over the tape, or you will never be able to pull it up. Be careful here, because my sewing machine, at least, wants to pull the hair apart, even though it is taped. Just feed the hair through without letting the machine pull it out of shape.
VERY CAREFULLY pull the tape off of the hair. Make sure to hold down the hair when you pull the tape off, because it will rip out all of your stitches if you just pull. It will kind of pull the embroidery floss apart, but don't worry, just use the other side when you stitch it on the amigurumi's head.
Place the bottom piece of embroidery floss on the amigurumi's head, like in the pictures. Try and make it as even as possible on the sides, and don't let it get too low in the back. Sew it in place with either invisible thread or a matching hair color thread. I always use invisible thread, but a matching color thread works just as well.
Now place the top piece on the head. Make sure that it covers the seam from the other hair you just put on. You can always tug at it a little to cover everything if you made it a little small. Sew this piece into place as well.
Cut all of the loops out of the hair. Make sure you cut both the top and the bottom pieces of the hair. Cut the hair as short as you want, but make sure the top piece is always long enough to cover the seam of the bottom piece. Don't cut in a straight line, try and mess it up a little to make it look more natural. You can also try and make it more even than I did, lol.
Viola! You're done. I hope this was easy to understand. If anyone has any questions, feel free to leave a comment here or e-mail me at artoo1121 at gmail.com.