Better Quality Strings
In one of my compositions, the cello has to play sixteenth notes at 120. When I added the piano part along with it, the cello was barely audible, even at fortissimo with marcatos. The solo strings in MuseScore, I've found, are quieter at the start of the note. Can you fix this?
Comments
Have you also tried to vary the range of dynamic?
https://musescore.org/en/handbook/dynamics-0#range-for-dynamics-text
You want to attach here the score, or only part of it?
Marcatos, in shortening the note, would probably make the problem worse—sforzato accents (>) should give better results.
In general, the sounds MuseScore uses for playback come from whatever SoundFont is loaded into MuseScore's Synthesizer. Some other recommendations are at https://musescore.org/en/node/36171#list —you might find one that has more aggressive attacks in the strings.
The tradeoff is always, if the note has a quicker attack it will sound louder for short notes to be sure, but lower passages that should sound legato won't. So it's a tricky balance - you trade on problem for another. Loading a second soundfont so you can choose the one most appropriate for a particular piece - or change int he middle of a piece via the Instrument text - is pretty much the only way around this.