Change Part of an instrument

So, you know how we can have different parts in MuseScore? (Default is that Part 1 is Blue, Part 2 is Green, etc.) I want to change an entire instrument to another Part. I just can't figure out how.
I've searched through other posts and how to's and such for a good hour+ now, and I can't find this info anywhere.

Is it even possible?

My setup is this:

Flute
Violin
Soprano
Alto

But they are all currently on Part 1. What I would like, is this:

Flute - Part 4
Violin - Part 3
Soprano - Part 2
Alto - Part 1

If you know how to do this, your help would be greatly appreciated!!