Has anybody got their audio out working on the Veon TV?

I've connected my Hi-Fi system, changed the input to AUX on the Hi-Fi, yet the sound still comes from the TV speakers. How do I get my speaker to play the sound? I can't find anything in the TV config to force sound to the audio out jacks.

Link to manual 49" version of 4K TV.

Edit:

Sound keeps playing on TV, no matter the input

• DTV
• Chromecast via HDMI
• PC via HDMI

I have also changed between the HDMI & HDMI (ARC) ports.