So, there I was, typing away, loving the whole Scrivener experience. And all of a sudden the default text size, I suppose due to my quick typing and therefore inadvertently creating some “hot key” issue, is HUGE. And I cannot change it back. And here is the most puzzling thing. The size of the text is the same - Courier New, size 12. And yet the text is like 4 times the size. I don’t know how to turn it off as I have no clue as to how I even turned it on. I am flustered writing like this, like I am some sort of blind damned giant! What is this!???!?!?!?!? 
You probably switched the view. Down at the bottom, you can adjust it back. 
Notice the 130% on the attached screengrab. Change the percentage by clicking the small down arrow next to it
