Marching Percussion Ruined?

Do i have to rewrite all of my marching percussion arrangements? I used 2.0 then 3.0, now everything on the staves are different in 4.0. If not, can I downgrade? I tried downloading Musescore 3 but it was a link for Musescore 4. Im guessing I just need an older version of Musescore, which I no longer have because that was on another PC.