I can't keep my Youtube account settings keep from changing?

More specifically, my video playback quality keeps changing. I choose %26quot;I have a fast connection. Always play higher-quality video when it's available.%26quot; But when I watch videos on other computers, it keeps playing videos in normal quality. Is there anyway to actually make the setting stick?I can't keep my Youtube account settings keep from changing?that setting is only for one comp i suppose