If you aren't getting any sound when you try to play something in either Disney+ or Netflix, try this :

1) Go to device settings / audio
2) Change surround sound from automatic to manual
3) Scroll down to the various audio formats and select them all EXCEPT FOR the first and third option.

Exit out and you should now have audio when you play stuff in those apps.

NOTE: If you're not experiencing audio problems in these apps, you don't have to do this.