PS3 HDMI Output back to S Video- FU*K

Guys, one of you must be able to sort this one, I set my PS3 up on the HDMI 50" in the living room for a while. All good, but when I took it back into the back room the TV is 720HD the same as the living room but the output from the PS has to be S Video instead of HDMI??**?
Now the PS3 started on the back room Tv and when I took it to the front room I had to switch it to HDMI, problem is I can't switch the bastard back. I follow the instructions in video out options, when finished it asks you to confirm your selection and then says it will revert back if the output isn't correct, well of course its going to revert its set up with HDMI!
If I go to the TV in the back room and plug everything in I cant get any picture because the bastard is set up as HDMI, cant get a picture to right the bastard !!!!!!!!
So you gurus WTF am I doing wrong?
I'm gonna have another crack at it, if it doesn't work then I'm gonna give it what for
I dont want to buy another TV for the back room just cus it hasnt got HDMI input, GRRRRRRRRRRRRRRRRRRRRRR technology doesnt suit this caveman
HELP PLEASE
Now the PS3 started on the back room Tv and when I took it to the front room I had to switch it to HDMI, problem is I can't switch the bastard back. I follow the instructions in video out options, when finished it asks you to confirm your selection and then says it will revert back if the output isn't correct, well of course its going to revert its set up with HDMI!
If I go to the TV in the back room and plug everything in I cant get any picture because the bastard is set up as HDMI, cant get a picture to right the bastard !!!!!!!!
So you gurus WTF am I doing wrong?
I'm gonna have another crack at it, if it doesn't work then I'm gonna give it what for

I dont want to buy another TV for the back room just cus it hasnt got HDMI input, GRRRRRRRRRRRRRRRRRRRRRR technology doesnt suit this caveman

HELP PLEASE