YouTube on my nexus 5 seems to be set to auto quality as default even though when I look at the quality playing currently it is not set on auto but rather something like 360p or 720p (it keeps changing). I try to change it to something else like 240p but it won't let me select it now. This only started happened since yesterday as before I could freely set my quality without any problems. I have looked for solutions online but found nothing and am wondering if I am the only one having this problem?

Suggestions?

PS: this matters because watching a youtube clip on 1080p kills my data limit for the month instead of watching 240p videos!!!