Lap top brightness dims when pluged in?

Hi, so I have this hp lap top. so what happens is lap tops have this power save mode thing which makes screen dimmer when you unplug, the problem however is that mine will go dim while pluged in if i unplug and replug somewhere else which is a huge pain in the ***. I need to kow how to turn off this power save mode thing altogether so it will never go dim but i dont know where to turn it off and even at max brightness its hard to type when screen is on power save mode (dim).