Probably too obscure a problem to garner a solution, but here goes. In OneNote For Windows 10, (as in OneNote included with various Office Suites) I use "Draw...Shapes...Line" all the time when I'm teaching graphing to my high school students. The line always used to appear with two 'selection circles' at either end, allowing me to have total control how to change slope of the line as well as sliding it around the screen. For a month or so, the line appears inside a rectangular selection box. Meaning I can still slide it around and stretch it but I cannot grab one end of the line and change its slope. This feature still works properly in the other Office apps. Probably a tiny bit of code that someone could change back in OneNote if it was brought to their attention.