Adjusting Audio Files

Hello there-  I am have imported my audio files into my PowerPoint deck using Articulate Studio and there is one slide that the audio is a bit louder than the rest.  I attempted to use the instructions from this article https://community.articulate.com/series/articulate-presenter-13/articles/editing-audio-in-articulate-presenter# but the sound changes when I used the volume adjuster are not taking into account, or when I adjust the volume, and it is also erasing the entire audio file if I move it more.  The audio files are in a .wma format. Any suggestions?