Ps3 wont show video on tv?

my ps3 is fairly new and the cords i just unwrapped yesterday cause i had benn using hdmi. with Hdmi cause im at my grandmas it works fine at home. at grandmas the ps3 has no sound and is blurry. when i tried to hook up the red,white, and yellow ones it wont show anything but a blue screen. yes its turned on. and theirs nothing wrong with it seeing as how i can play it on Hdmi. how can i fix this?