Vera Vieira

Today, just a beginner Cakewalk user, had a piece composed elsewhere played in playback (sorry if my language is not write), I couldn't stop it from repating, either. After the fourth time, having tried things in between, I finally clicked the stop button and it stopped. Then, I tried to import another piece, but when it started, it mixed with the previous piece where it had stopped... Is there something I am missing? I'm totally new here... By the way, I'm using the 2021.6 Early Access version.