Why are some points on a fit spline white, some black?

i seem not to be able to move the white ones. how did they get that way? how can i make them able to move?

can’t i add a pic here?


The White are moveable Control, or Fit Points depending on the Spline type chosen.
The Black are Locked Points.

Click on any Point to Lock/Unlock, just Tap the Lock Icon and it will reverse the current setting:

how did they get locked?

Locking works in the manner explained.
If it happens regularly collect as much detail as possible and submit it as a Bug to the S3D Team.