When you have finished creating your Grids, Lock the Layer in ALL your Layer Combinations, which will make it very difficult to accidentally edit its position.
Holding the Shift key when placing an element locks the direction, but you can also force hold a specific Angle or X or Y coordinate value. Hit Alt+A, Alt+X or Alt+Y whilst placing the element.
You can lock a Layer to prevent its contents from accidental modification by bringing up the Layer Settings dialog box Ctrl+l (PC), Command+l (MAC) and clicking on the lock icon to lock the layer. If a Layer is locked, the elements on it cannot be edited or deleted. Note: No new elements can placed on