Drawing a line with line tool or pen tool (changing width and general editing)...

Hello,

Having given up on the line tool and, instead, resorting to the pen tool to draw line segments, things seemed to be going just fine. I could actually change the width by updating the pixel value (next to 'Stroke' at the top). Then, all of a sudden, instead of drawing a new line segment at each anchor point, it starts creating shapes. I.e. three anchor points resulted in the drawing of a triangle instead of placing two line segments. This had been working fine, then boom! Triangles. Why are simple geometric shapes in Photoshop (v 21.1.3) so poorly implemented (I won't bother going into the line tool and the problems I had changing the width both whilst creating a new line and retroactively editing an existing one).

Thanks,

Matthew