Mike Posner changed the lyrics to his most famous song and bucked a social media trend ... and he's explaining why he views the past a lot differently than most folks right now. The "I Took a Pill in Ibiza" singer joined us on "TMZ Live" Friday, and we asked him about the big lyrical change he made to his song ... at a time when folks on social media are looking back on 2016 with fond memories. Mike's song caught fire in 2016 ... but he says he wasn't truly happy when he was singing about