Soundfonts being changed in MuseScore without the user doing anything with them

I don't know who's changing (AND RUINING) the soundbites, but the Tam-Tam sounded right earlier today but now it just sounds like a crash cymbal. I also had the trombone, tuba, bari-sax, and bass clarinet playing a part together and they were correctly balanced, but now the bari and trombone absolutely overpower the other two even though I did nothing with the volume. They are the same dynamic and same volume in the mixer, so please stop messing up the volume and quality. Additionally, before, they didn't sound buzzy, like an electrical arc being transferred over a few centimeters of air, but now they do. Just fix the soundbites and stop messing my stuff up PLEASE!!