MIDI Importing as "Grand Piano"

Hi! I export MIDI from Logic Pro X to import and edit in MuseScore. However, MuseScore always import as GrandPiano instrument, and group my instruments under the pianos two staves.

Right now I'm trying to import a midi file containing four trombone tracks. They show up as two Grand Piano tracks, as seen in the picture. The "Muse Score Instrument" menu doesn't give me any options.

How do I make Muse Score understand that I want these as four separate tracks? My workaround has been to copy and paste into new tracks, but it's a bit tiresome and there should be a better way to do it...

Best,
Joel