Default notification tone on Whatsapp

[acer]

Hi, would anyone know why the Whatsapp on my Xperia Z always uses the (I think it is default) tone even when I have selected a different tone? The 'default tone' is useless because it is too soft even when the ring tone is set to highest.

I selected the new notification tone via the Whatsapp.

[Samuel1]

Does the phone play the default phone notification tone or some default tone for whatsapp? Haven't used whatsapp myself so I need some more info to try sort this out.