You could buy the kind of bowl that simply won't turn over or you could train him. Get him to play with it and turn it over in the process of playing and then say "No" or "uh oh", not with anger or emotion but letting him know it is wrong. Make an unhappy face as you say it. You could say "Bad" and shake your head, using your hands to make an abrupt stop signal in the air. This will teach him this action of the turning the bowl over makes you unhappy or is not good - however he can perceive it. Whatever you do don't treat him during this aspect of training. Go through this turning over by him during play several times for only short periods of time - 2 -3 minutes and stop but 3 - 4 times a day. Let him get the idea that mommie isn't angry or mad but this is just
not something to be done.
When he seems to have gotten a handle that it is not good to turn it over, try to get him to do it again through play and the instant he hesitates or looks to you as if to say - "But you don't like what I'm about to do", lavish him with love and praise and give a treat. You want him to know that hesitating in turning the bowl over is what you do want and it is good to refrain from doing that now - and that he gets a big, big happy loving reward when he hesitates and doesn't do it. It is a 2-step process but believe me, dogs are smart enough to "get it" in this process. Just don't give a command to turn it over - let that come from him, through play or romping around, if at all possible.
If he just won't ever turn it over during play with you, you may try turning the bowl over yourself and giving the negative signals and see if he can get that message just the same - that the bowl going over no matter who does it, is not good.
Of perhaps you could take the food bowl up when you are gone and leave some food on a stone slate or something hard to move or buy one of those food dispensers that is usually too large and bulky for a little dog to turn over or try to play with.
Just some ideas to try if you want. Good luck!
