How to force 720p video quality in embed link?

Hello everyone,
I am trying to make a survey where multiple videos from Youtube will be displayed. I inserted these videos into survey by using their HTML. All videos are working fine in the survey.
I used the following format to insert my Youtube videos:
My question is how can I force these videos to start playing at 720p video quality? In other words, regardless of the internet connection, I want each of the videos to start playing at 720p by default.
I thought I could do it by inserting a parameter in the embed link. By following this instructions I changed the links by adding following parameter right after the (VideoID): ?rel=0&vq=hd720
Unfortunately it doesn't seem to be working. Do you have any suggestion about what might be wrong in my link? Or do you have any other alternatives for me? I hope I was clear enough to explain my problem. Thank you so much in advance.