Why are my V brakes spongy/squishy and not firm

I have a beach cruiser with v brakes.. bike is a giant simple 7 and about 7 years old.. original parts.. i just put new pads on but when i pull the rear brake it goes almost to the hand grip.. pads are on correct. when i pull the lever i can see the pads sliding down the rim and not pushing side to side and making it a nice firm brake pull.. why is it doing this? why are they sliding down the rim??? i am looking at my neighbours bike., .also v brakes and it s a new bike.. brakes are rock solid.. and very firk.. do i need a new cable and housing? am i doing something wrong?? i tried with the tension screw on the brake lever in and out.. i tried with the cable tight at the cable lock are... what do i do to get a rock solid brake feel?