S9+ Screen Record Mic not playing back

[LordEmostache]

I recorded a video with phone sound + Mic sound and it originally played perfectly fine, I could hear both the sound from the phone and the sound recorded from the built-in Mic. However, when I exited the gallery app and returned, when I play the video I can now only hear the internal recording, I believe the Mic recording is still on the video but it is incredibly quiet and barely audible now. Does anyone know how to fix this/change the volume levels of the internal audio vs the Mic audio on the video?

[AndrewL]

@LordEmostache: Can you try opening the video > Tap the pencil symbol at the bottom of the screen to enter 'Edit' mode > Look for the editing options at the bottom of the screen, and swipe over to the musical note symbol > Video Volume > Adjust this to your preference. Are you able to hear the Mic audio now? 

[LordEmostache]

No, it just changes the internal recording volume