Cabrinha68

Hi all, ive just bought the arc air gt challenge and want to red the speed of the cars for the childre. I went onto the app and reduced the first one down to 25 percent which was perfec. I then went to do the second car on the inner slot of the track and I reduced this down to 25 percent but it liter crawls along at a snails pace. Any ideas what I need to do before Xmas day? thanks