No matter what if water is pooling then it's a low point. Remembers that it needs to slope downward on two planes; from back to front and from right to left (towards whichever side the gutter is on). Other people in the thread were correct about the corner joints leaking. I would seal those up again to be sure. To change the slope you should be able to unscrew it from the fascia and screw it back in. If it uses long aluminum nails then you'll have to reposition those.