When I modify settings, in any software, I like to have an "Apply" button that doesn't close the window but makes the changes effective.
Example : I want to change the color of my canvas.
I open the settings, change the color to one I like, then save (which closes the settings window). Finally, I don't like the color and want to use another one. I open again the settings window, change the color again, then save (which closes the window again) and so on...
It's bothering to have to open the window each time.
So I think, having this kind of button in the user settings window would make the settings modification more comfortable for the user.