How to change the category when uploading a score

Hi all,

On Musescore.com I found this score here https://musescore.com/user/27887176/scores/5552774 where the category/filter is set to "Men's Choir," but when I playback the score, all the parts sound like grand pianos. Does anyone know how I can do this on my scores too? I want to upload a choir score but have the parts play piano on playback, while keeping the choir filter.