Training a great dane that does whatever it wants?
I have no clue where to start. How can u teach a great dane that if its not given to him, its not his. he's a puppy (21 months) but he's already stolen 3 WHOLE dinners, including a thanksgiving dinner which would of lasted more then one day. he ate better then us. the people i live with think thats funny. he steals food at any oppurtinuty its like you have to fight him to have your own cuz hes so huge. to him its worth it cuz he gets yelled at, but he still gets the food. (u can be yelling at him as hes still taking it so that shows 100% that he dont give a damn) so i try & take it to the next level after he stole off my 1 year old daughters tray and not give him any treats but give the other dog in front of him & they get pissed at me about it. its not my dog but i am a person so i am over the dog & im doing what i can do to work with him bc hes behavior is unacceptable. i dont feel like any dog should be liked to much to get trained and he is spoiled way past rotten & the food isnt the only thing he acts up with.
really 1st answer, its all that? this isnt my dog & the problems are over welming but theres only so much i can do, i cant take him out of the bed that he sleeps in with his mommy and daddy, so yes he thinks he is king.

Sane adults TRAIN & discipline dogs.
The weak ignorant & lazy allow animals to rule humans.
That nasty beast has been an adult dog for a year-it is NOT a "puppy"!
Google NILIF and start trying to put some of that into practice with consistency. Would need on board all people dealing with the dog.
Also try the old tin can trick. Tie a load of cans together (drinks cans are good as they have the ringpull. Put them on a worktop surface along with something tasty tied to it. Preferably over a tiled surface where the cans will be noisy.
Put it all as bait and stand back out of the way so that he doesn’t associate it with you. Wait for the clatter. He should think WTF and get the fright of his life.
Here’s hoping.
You need to get all the people you live with to be consistent with training. Don’t feed him off your plate, so he wont associate your food as his food, because your food, is YOUR food. I would work with some basic commands, such as sit, stay and leave it. Also it might help if you keep the dog out of the kitchen while you are in there eating a preparing food. He’ll have to get his ‘sit stay’ down first and you can put him in a sit stay outside of the kitchen. If he comes in, put him back in a sit stay. Make sure you start off slowly. Don’t expect him to be able to stay for the full time you are in there are first. Build up the time he is there and soon he will be able to stay out. Also body block him from coming in. Which is just basically walking into him, so he has to back up. Then do the sit stay, etc.
The place command might also be helpful. When you are eating dinner, or any food…Have the dog go to place. Which could be a rug in the corner or his doggy bed or crate…again start training off slowly and give lots of praise and treats when he does something nice.
Hope this helps. You need to be consistent, he can’t sometimes be allowed to do something and then other times not be allowed to do something. So try and get everyone in the house on board. It’s going to take some work, but it will be worth it. Plus training your dog is a good way to bond and have fun with your pet. And please, please, please, don’t hit your dog.
**Edit** Oh, I didn’t realize it wasn’t your dog at all. I thought maybe you had some say with it. Honestly your problem then lies with the owners. Try talking to them…try reasoning with them, if they don’t listen…I don’t know what else to do, except move which I assume isn’t an option. Maybe get the them a dog training book? I dunno, sorry.