I usually do just that.
However it choosing that setup upon video opening is always a great sign that my line and account is working as it should.
The last month had to select 720p and pause and let it buffer for ages.
Things are looking up!
If you use firefox try adding the add-on called "YouTube Center" if you're interested.
It works on chrome as well but is more tricky to get working.
It allows you to set a lot of custom settings for youtube.
I used to use it to disable dash playback, so the whole video would buffer at once.
But since youtube changed the way its players work especially with the HTML5 player, dash only works on the old player.
Still worth a look if you're interested.