Instrument problem with opening my old scores in MuseScore 4

Have a TON of old scores of a cappella arrangements that I would LOVE to transfer over to MuseScore 4. Because of the lack of clarity in the "voice" instruments of MuseScore 3, I had them all set to Grand Piano in the mixer. However, when I open them in MuseScore 4, it tries to be helpful and convert all the parts back to the "voice" instruments.

Is there a way to stop this from happening? Or alternatively, is there a quick and easy way to switch all the sounds back to the MS Basic Grand Piano (NOT the new Muse Sounds Grand Piano, having issues with how that sounds in this context). I'm not seeing it an option that wouldn't take several annoying steps. Any help would be appreciated?