You can use a script with the Adjust Window [Maximize] step to pop the window out to it's largest size. You can use File Options to set this to run when the file is opened.
"...how would i get it to automatically look the same on any size screen i load the program on to?"
You can't really, screens vary too much in both resolution and vertical vs horizontal proportions. You can take steps to minimize these differences but you can't completely eliminate them.
You can write scripts that check the screen size (they use get functions). You can change the anchor settings on layout objects so that they space themselves out as the window size is changed, but this is far from perfect.