How do I turn off or change the notification sound on Facebook?

How do I tu off or change the notification sound on Facebook?

Hi guys, I've only been using Facebook for a few days and I want to ask is there any way to disable or change the notification sound on Facebook? It makes me feel uncomfortable and aoying. That's why I want to tu it off, but don't know where to start and how? Hope, get help from everyone.

Thanks in advance!