Support for academic differentiation

I would like the ability to change the share settings while I am presenting, this would help at the academic level to enable differentiation as there are specific times that I want the students to add their ideas to the board but I don’t want them to drag that out.  Right now I have to stop the presentation to change the share settings for them to be able to edit.  Additionally it would be nice if I could have a timer feature on the share options or only allow them to edit on specific frames.