Squeaking has changed...

Hey, I used to have a squeak problem at lights, or when in neutral. I would get that all comon squeaking belt, but when I was in gear, or pushing the gas, the squeak would magically dissapear. Well... things have changed.

Now, I still have that same annoying as hell stop sign squeak, but also, now I can hear it while driving, and it picks up speed according to how fast I accelerate/ am moving. When I am in my drive way, I applied belt dressing to see if I was targeting the right belt, and I had been all along, it is the fan belt, the dressing will hold the squeak for a total of about a minute, then it will slowly come back until it is once again at full force. I have tried tightening, and replacing belts, where do I turn to now. What caused the squeak to come when I am pressing the gas Now?

PLEASE HELP!!

Thanks.