Fixing the X-Men movie universe again.

Film   Following on from my outlandish pronouncements and head-scratching the other day on the state of the X-Men film universe and the repair thereof,  Bryan Singer's given an interview to Empire which encounters this very topic. He says:

"I’m taking into account every movie – I’m not just grabbing my first two movies and First Class and smashing them together. I’m taking into account the entire universe as it’s been laid out so far on the screen, and really respecting it and trying to work with that. People took things in various directions, so there’s some clean-up. But ultimately I’m not just ignoring them either.""

Key phrase italicised.  Whatever could that mean.  How do you clean up something which has already been seen on screen?  Retcon.  Retcon.