I'm no expert by any means, but take a look at the radio/entertainment center unit. Not sure if yours is in the same location, but working from the pictures on the forest river web site, I'm referring to the one shown on the port side across from the TV in the gallery pictures.
Take a look there and/or in the manual for something labeled Zone 1, Zone 2, etc. That generally refers to which sets of speakers are on or off. Zone 1=inside, Zone 2=outside, etc.
on mine (2019) the radio has A, B and C speaker channels.
there is a button on the front of radio (I think it says zone) that switches channels
Switch Zone to A and set your inside volume, set zone to B and you can set your outside volume. (It will play both zones the same time but you need to change zones on radio to adjust the volume for each zone independently)
Don't forget to turn zone B back to volume 0 when you go inside at night
Linear Mode
