Starcraft II life bars in the game?

Noob question time! I know how to turn life bars in replays but I watch a video on youtube and it was recorded live and life bar was on and I didnt know you could do that! I know lifebars I can turn on by clickin " or | or some random key on my keybored but as soon as I unclick that they turn off so how do I keep them on? I am use to life bars in other RTS's