Sound playback

Hi, so I've composed a piece for a school assignment

I've composed for an orchestra but the trombone is the solo instrument.

The problem is that the other instruments (mainly trumpet & flute) are too loud when I play it back, is there a way of lowering their sound so that I can hear the playback better?

Furthermore, is there a way of exporting my piece (as in the audio) from Musescore?

Thanks
Jono