Hello, I love my maclaren triumph but I cannot seem to undo the clip on the back seat of the top of my daughter's shoulder straps, so although I can lengthen the straps they come from the back seat of the stroller under the height of her shoulder which is uncomfortable. Does anyone know how the plastic clip comes undone please so it can slip though the back of the seat and be re-insterted in one of the higher shoulder strap slots please. It is probably very simple but I cannot work it out. Many thanks