They are awful. IIRC if it has three dots, it's for accessibility only - you don't need to press it. If it has the vague hand symbol, it will probably light u

They are awful. IIRC if it has three dots, it's for accessibility only - you don't need to press it. If it has the vague hand symbol, it will probably light up when you "tap" it, but may not actually do anything you notice - one near us it doesn't speed up the light, it just makes it last longer. But for others it might also be necessary to tap it to make the light change!