This indicator marks what is known as the BB system - Marks on your chart the premarket high and low, current intraday high and low and yesterday's high and low. For the style of the line you can only change the colour, if you make the line a different style it shouldn't show up because if it did it makes the lines ugly.
Pick and select which levels you would like using the indicator and you can also turn on and off the labels if you don't want them.