Here you can change the grid color, or turn your grid visibility and snapping options on or off on a single screen. You can also change your grid size; the default is 18x18 pixels, but you can set the width and height to anything that you please--and you aren't constrained to a perfectly square grid.
You can also adjust your snap accuracy; the options available are fairly self-explanatory, but you should try experimenting with them to see how they affect your work on your stage.
