Toyota Repair: High beams, high beams, high beam

Question
2000 Avalon.  I cannot get my high beams to stay on.  With headlights on, when I pull switch arm for high beams the high beams will come on but will not stay on when I release the arm.

Answer
Maybe I'm not understanding correctly, when the switch is pulled up it is for momentary high beam only and the high beams go off when releasing, when the switch is pushed down the high beams will stay on until the switch is returned, please clarify this a little more, thank you.