Air, light and heat affect olive oil, so you should make sure the bottle is properly closed and store it at room temperature out of direct sunlight. 

Oil stored in the refrigerator will go cloudy and may become solid. If this happens take the oil out of the fridge and store in the pantry. The colour will return to normal.

Oil in casks, or in dark glass will last longer than oil in clear bottles or plastic.

An oil's colour does not indicate quality.