Highchart's docs don't explicitly state the order of precedence, but it seems implied (and definitely intuitive) that the global options are overridden by the series type options which are overridden by the individual series options.
However, it seems that the series type options are applied first, get overridden by the global options, and are finally overridden by the individual series.
This was an attempt to reproduce the issue from https://github.com/highslide-software/highcharts.com/issues/1132, but in jsFiddle I am not able to. It's a tricky bug.