Those very thick lines should be narrow lines and I have tried everything. Will you please, share some insight? Thank you! Images are attached. I have the same trouble on handrails.
For the 3D pen settings, look at the Finish > Tread and Flight panels. The panel in your screen shot is for the plan display.
Thank you kindly for your reply. The solution was to change the model view options for both railings and stairs to full instead of simplified. Please, see attached.