You can change this under the settings on the mac app (the options are quiet, normal, and loud)
2) The Volume level on the player itself is set lower than usual
This can be changed in the bottom right of the app using the slider
If neither of these are the case, make sure you're on the most recent version of the app. If you are are and are still having problems, it could be as simple as logging out and back in, or even restarting your device!
Let me know if you're still having issues and I'll see what I can do!