I finally got the audio delay fixed. I was accessing the settings menu using the touch controls on the monitor and couldn't find the audio delay option. Eventually I used the remote to access the settings menu and was surprised to see a different set of options, including adjusting the audio delay. I don't know why this option isn't available using the monitor controls but thankfully we haven't lost the remotes.
Now we need to find a simpler/faster way to actually select the movie audio to play over the car's speakers. Right now, we have to first go into the bluetooth settings and select the RES bluetooth to connect, then go back to the audio settings and change the source to bluetooth.
Even though the RES is set as the favorite, the system defaults to our phones whenever we turn on the car, so we have to go through this process anytime we play a movie (plus, when we turn on the car, the audio source goes back to FM so we also have to change the source back to bluetooth). Fortunately we only use the RES on long road trips so we don't deal with this often but it is still really annoying. There should just be a single button, 'Play RES Audio', that does all of the bluetooth and changing audio sources for you.