Hi, the blue plastic on the lips, is the 'Click' system, unfortunately this can sometimes move out of place due to the nature of the product, this can be easily reset by pushing it into the middle of the board before laying, once you hear the 'click', that means the blue plastic has dislodged into the other board, which is how the boards are locked into place. The plastic cannot move after this.
A jigsaw, loaded with a new/sharp blade should make cutting the boards down fairly easy.
We are glad to hear that you are enjoying the flooring despite the hurdles you had come across while fitting.