Can someone please tell me how you “lock in” a Insert Mesh Curve??!!! I draw a tube, set it up how I want it, then when I go to draw a new one, it erases the old one and draws the new one??!!! I’ve tried masking everything, to unmasking, to changing brushes. please help! 
When you’re done drawing the tube, click once on the underlying mesh to delete the curve. Then you can draw the next tube. Same as clicking ‘Delete’ in ‘Stroke > Curve Functions’.
Holy Cow, thank you! I was looking everywhere on the net, and watching tutorials, and no one that i recall had mentioned this. THANK YOU!!!
No problem! 