I have an app in which the pixel size is 480(height)x800(width), and have it all set up, yet when i debug it into two different android with diferent screen sizes, one fits, while the other isn't fully screened on there. i tried coding it the way some of the forums talked about yet it doesn't seem to work. So i'm hoping if anyone out there has any idea on what i need to do to make it fit into the second screen, please help.
Flash has different stage scale modes, that can help with this. The default scale mode is showAll, which will do what you're seeing. You could stay in that mode and just have extra graphics off the edges of the stage, that will appear on wider or taller devices. An alternative is noBorder, which would make the center area of the stage fill the screen. On wider screens you would lose a bit of the sides of the stage, and on taller devices you would lose some of the top and bottom.
Put one of these lines early in your document class, to see the different effect:
stage.scaleMode = "noBorder";
stage.scaleMode = "showAll";