Short code display on top of my page

Hey,
Was just wondering why when using the shortcodes on a page it displays on top of everything else rather than the location I’ve placed it in, could you advise me on how I can change this.

I’ve managed to discover a fix for the PHP …..ob_start();

return ob_get_clean(); …etc

but I have no idea where it should go.

just some guidance would be appreciated.

Thanks