Musescore 3 and V4 compatible?

I have yet to switch from Musescore 3 to Musescore 4. The reason is that when I did attempt to change, none of my previous scores composed in Musescore 3 were compatible with Musescore 4. So, if I used 4, I couldn't revisit any prior work. Has this problem been considered or solved? And if so, can someone let me know the solution?