Asigning midi instruments to Dorico tracks

I’m a Finale veteran trying to learn Dorico. I typically deal with choral music so my tracks are labeled Soprano, Alto Tenor and Bass. However, I like the midi playback to all be via piano. When I label staves in Dorico with Soprano, Alto, Tenor and Bass I get a lot of vocal “Ahhs”. How can I replace the ahhs with piano sounds in the exported midi while maintaining the midi track names of Soprano, Alto, Tenor and Bass for my end users?

Welcome back, Bick!