How do you use the Curves modifier to make a smile or different shape? I was following along with Blender Guru's video on how to make a Teddy Bear, and I got to the point where he is talking about how he made the mouth. He uses a Bezier Curve and a Screws Modifier. Whenever I try to replicate it, the Screw is never aligned, and does not curve the same way his does. When I move the Screws, it curves and twists around, and I know that is because of the Bezier curve. I have tried to play around with it, but I can't get the same results that is in the video.
Here is the Blend file: http://www.mediafire.com/file/i14byvl9xjo2jkr/Teddy.blend/file
Any help is appreciated. The curves modifier is a bit strange to me, but I want to learn more as to how he was able to manipulate it the way he did for the mouth.
First I would select your piece of jarn and press Alt + R to reset the rotation. I would do the alignment with the curve with translation (with G) and the axis-buttons on the settings of the Curve modifier alone. Then i would only manipulate the curve, not the jarn.
Apart from basic translation an rotation of the vertices of the curve, i would also Subdivide to create extra vertices for more control.
Lastly, and most importantly, it is useful to know you can rotate a curve vertex in Edit Mode around the length of the curve (in other words: adjust the tilt of the vertex) by pressing Ctrl + T.
twisted and untwisted:

Hope that helps.