By default sprites are created in world coordinates and TAgkScene.SetViewOffset can be used to move around the world. Set this property to True to instead fix the sprite to the screen so it will move with the viewport when the viewport is moved around. 

You can still reposition a sprite that is fixed to the screen, it only affects what happens when the viewport is moved. You should not use physics or collision commands on sprites fixed to the screen as their debug shapes will not line up and they will interfere with physics sprites not fixed to the screen.

TAgkSprite Properties