Youtube Embed Shortcode Not Working

Ok so I’m pretty new to this, and I’ve been having a problem with embedding a Youtube video and editing the width and height.

I’ve been doing this:

[embed width=600 height=300]https://www.youtube.com/watch?v=e4FR0-vOIFw[/embed]

And yet some videos come out as more square then others … It’s as though some are in HD and some are in standard def – the width and height only seem to make the video smaller or bigger and not actually change the scale like I need.

Any help would be greatly appreciated!