Technically unchecking the box doesn't work - you can't draw tracks at random angles, which comes handy during RF layout. I personally use it quite often. Since there are no circular tracks in KiCad, for RF tracks I draw a circular line on the drawing layer and then approximate it with the short sections of the track drawn at variable angles on top of it.
Along the same lines: the automatic track drawing in OpenGL mode, when the software decides the track posture and switching it with "/" shortcut has very little bearing on the way the finished track looks is extremely annoying. 80% of the time it is useful but when you need your track to go a certain way it will drive you nuts! I can't tell you how many times I attempted to draw a track that I wanted to go in a certain way, just to have the OpenGL mode switch it at the last moment. Solution for the both issues would be an option when you can disable the "smart" track drawing mode and have the simple mode enabled, when you can just draw one segment at a time (preferably with a keyboard shortcut)
Yup, this is one of those settings that has its own option for legacy as for OpenGL. I was on an option unifying spree until I got a job and suddenly had no time >_>
In OpenGL you can do this through Preferences-
"Along the same lines": _please_ open separate reports for separate issues. We can't keep track of multiple issues per report.