MuseScore 4 - Changing instruments in the mixer

I use MuseScore to prepare sing-along practice recordings for individual parts for my church choir.

In MuseScore 3 I found it very useful to alter the instruments in the Mixer prior to export to MP3.

To make sure that the featured part of the SATB ensemble was clear and distinct, I would render it with a piano while other three parts played at reduced volume with strings or winds.

I actually found that the FM electric piano made a good dominant voice, and the Tine electric piano was good for the subordinates.

The "choral" voices are a little too mushy for for note input and proofing. I prefer to do that in straight acoustic piano.

I see that instruments can be swapped on each stave through the instruments pallette, but it's a lot more convenient to to it in the Mixer, where I also set the levels.

Please return this functionality to the Mixer in MuseScore 4.