hi there im just wondering why cant I change my kiai sound ? everytime I get mad because of that

What problems are you having? Is there an error when you upload a new clip or do you just don't know how to add a new clip?

I dont know to add a new clip when I try to change my current to another it says please select a file to upload I rly dont know what dose the mean

Search for kiai item in your inventory. Click on "edit", you will get to a page where you can browse and upload the sound.
Note- The sound file should be in .wav format, and 5 sec and lower in length.
-----
Also don't worry if play button doesn't work. As long as it says successful it will come in-game when starting a multiplayer game.