If the Previous Segment is a Dwell or a Constant-Velocity.
AND you want the Position and Velocity to 'flow' from the Previous Segment.
In these cases, the Position and Velocity at the End of Previous-Segment must be specified at the START of the Previous-Segment.
Thus, you must make the Previous-Segment active [so it becomes the Selected-Segment] and then edit its Start-Position. The Position is also the End of the Selected-Segment because it is a Dwell!, and thus the start of the Next-Segment you want to edit.