dynamics

I need my left hand to be "softer" than my right hand. (and further along in the piece I wrote, I actually need to switch roles and allow the left hand to be the stronger melody). however when I apply a dymanic, such as p or mp, it makes both hands the exact same softness. I was reading forums on how to either split the staff (create a second piano - one with treble and one with bass) or note properties. however when I highlight the selected note in the bass clef (or the few measures I need to be quieter), there is no "note properties" option, just a staff options or measure options. it is really frustrating to me, that there isn't the option to apply dynamics to individual clefs, or just for a few measures anyhow. i obviously plan on playing my written piece on a actual piano in real life, however if I were to make an .mp3 or sound clip of my written piece, it wouldn't sound anything like what it would in real life. I wrote my piece for a friend before her mother passed away, and it would be really cool to give her an .mp3 copy - but it sounds like crap because i don't have the option to control individual clef volumes. I am using the musescore app for windows 10 (version 2.3). maybe this is why? do I need to download version 3?