Yellow arrow points to the cover to remove to access the fridge switches....
Turn the two small clips on each bottom corner and remove the cover
Green switch is for AC and used when connected to AC power such as at a campground, in the driveway or via a generator
Red switch is for 12 volt...my recommendation is to use that ONLY when being towed by a vehicle and make sure the tow vehicle is charging the battery in the trailer and DO NOT LEAVE it on when the TV is off or over a period of time it might drain the TV battery too.
To run on propane. Make sure propane is in the lines then turn the knob to the left of the switches to the high position, and press the auto lighter switch (red) above the knob.
It sometimes takes a few pushes to get the system to ignite. You can tell if it is on by looking at the bottom of the silver tube (stack) that is all the way over to the right inside the compartment. Hard to see the flame, especially in full sunlight.
The knob on top, above the AC and 12 volt switches is for setting the fridge temp.
The red arrow points to the hot water heater (if you have one).