I notice that I have a pen icon in the Scribble tool in the Home tab, but you have a drawing icon there which is the same as the annoying icon you mentioned.

If you're using a mouse, you can Press and Hold the mouse button to draw and release to stop.

So, I guess you can change the scribble tool back to a pen icon and it may solve your problem.

(b.t.w. this is my first post in this forum. I want to clip the snapshot of the pen icon for your reference but don't know how to do. The "insert image" in the Quick Reply asks me for the URL but the screen shot is on my Mac's desktop. If you tell me how to insert it to the reply to this thread, I can include the image for your reference.)