I am trying to create a 3d sketch line for the side profile of a mouse.

However, I can not change the Y parameter value of the point online the same line, only the x and z-axis.

I have tried holding and dragging the points down as well as manually entering a value in the Y parameter box it will not let me, y value goes back to 0.00

Sometimes if I change the angle, I can get some points to work but it just seems to be completely random.

I am sure the 3d sketch was not created within a 2d sketch as I selected the top plane than selecting 3d sketch from the sketch drop down menu then using spline tool to create the line.