Second thing: In this video the get only 2 points in each curve but I couldn’t get. I’m getting lots of curves more than 200 like that how to solve this
take a look to the rebuild command. it could help you to reduce the control points of each curve and work more “freely”
when you use Interpolate crv tool to make a single segment, that segment already have degree 3 and 4 control points.
I assume you tried to make a planar curve, and discovered it was not planar after rotating out of the the front view
Did you use a snap for end/start point of the curve, but not for the other points when drawing the curve?
When the end- and start-point are not on your cplane, and the other points of the curve are, you will get a non- planar curve.