MDL Percussion in Musescore 3

I just recently updated my musescore to the 3rd version and the battery sounds seem to be set back to the default ones when it first came out. How do I change that? Also, all my scores that I made using Musescore 2 didn't download into the third version so I have to manually drag the scores into musescore 3. But when I press play, I can't hear my music being played. Is that a bug in the system or what?