Welcome to the forum.
In my layman's non-expert opinion, those don't look like propane shut-off valve handles IMO. Can you see any propane supply lines behind them? None are visible in your photo. Can you stick your camera/phone back there and get a shot of that assembly from behind?
Do you have an owner's manual? If not, one can probably be located online, so please advise.
You also might want to put your questions in the Land Yacht sub-forum:
. . . where you will have a more focused audience IMO.
Suggest that you shut off the main gas valve on the propane tank while you research those 3 handles. Do your propane appliances work?