@Razorwings18 For both position and size parameters, the X and Y are divided by UI.WIDTH and UI,HEIGHT, respectively. UI.WIDTH will always return 1280, and UI.HEIGHT will always return 720. If you want to get the real dimensions of the game window, you can use Game.ScreenResolution.Width (and Height).
To work around this you can do something like:
float adjustedWidth = (widthPixelsYouWant / (float)Game.ScreenResolution.Width) * UI.WIDTH;
float adjustedHeight = (heightPixelsYouWant / (float)Game.ScreenResolution.Height) * UI.HEIGHT;
Point pos = new Point((int)adjustedWidth, (int)adjustedHeight);
pos as the position parameter. Similar thing for the size.