Basic light exposure

Hi!

Sincere apologies for this being such a noob question but seeing as I’m a lecturer in audio and not game development, hopefully you’ll take pity on me!

I’m trying to set up a UE4 project for my game audio students (in 4.24 ) but the project I have, whilst otherwise perfect, renders much too dark when I go into play mode. I’m found the exposure EV100 dial in the viewport which when set to about -4 gets good results but this only applies to the editor viewport it seems. I made an attempt at changing things in the Post Process Volume but it doesn’t seem to make any difference to the exposure in either play or edit view.

I’m sure I’m missing something obvious here, hopefully someone can steer me in the right direction.
Thanks!
Andreas