Wrong notification sound

[Android Central Question]

Hi. Got my mate 20 pro yesterday. When my phone is in lock mode and I receive a WhatsApp it defaults to the SMS sound but if I'm busy on my phone and I receive a WhatsApp the right whatsapp sound comes through. Is this just a setting or what can I do. I've changed the WhatsApp sound in the Apps settings. Please advise. I'm not an active member here and if you can assist please email me @ Marien@vodamail.co.za
Much appreciated