I had been tracking some of my wife's shows, but decided to stop doing that. It left me with tons of episodes marked watched that I wanted to change to skipped or unwatched. I'm sure I could do that with the API, but I wrote a line of Jquery you can paste into console or convert to a bookmarklet to accomplish the same thing. Not sure if this is the right place to share it, but here it is in case anyone finds it useful.
status='2'; $('select[data-id]').each(function(i) {$(this).delay(2000).queue(function(next) { if ($(this).prop('selectedOptions')[0].value != status) { $(this).val(status); $(this).change(); } next(); } )});
If you want it to change to unwatched instead of skipped, change status='2' to status='' at the beginning of the line. Watched is 0, acquired is 1.