If you are not in curve editing mode, double click the continuous line to edit it.
The continuous line is yellow, has a red handle at the selected point and two dull red lines with circles at the end, indicating the tangent direction and magnitude.
The middle points are selected.
You can also use the Position dialog instead of entering coordinates.
Releasing the mouse button gives:
For more information on editing tangent handle see Editing a Bézier curve.