MuseScore 4 option to save in MuseScore 3 format?

Had I known the soundfont situation wasn't going to be updated until much later I would have saved this as a separate file but as of now (I know, I know! I was just excited to try out the new version) I'm stuck with a score I can no longer edit in MuseScore 3. Which I'm going to have to stick with for Harpsichord composition :)
Can I save in the previous format or how can I manually recover this score? As it won't display in MuseScore 3 now.
Love all the UI changes but going to have to stay with MS3 for the foreseeable. Hope you bring back the synth and soundfont funtionality back soon.
Hope someone knows how to do this or am I going to have to re-enter this score again?

cheers P.W. van Maale