Hello and welcome to the forum. I am not sure whether diet has a significant impact on behaviour although some additives found in poor quality foods might be problematic to some dogs. With this in mind it is good policy to buy the best quality product that is affordable.
It would be helpful to use the Dog Food Directory filters because you can tick the box for no red ingredients. Always look for something that has a clear ingredient list and has a named meat source at the top. If you need help using the filters please ask and we will try to assist. There is a thread here
that might be helpful.
Canagan dry food review is here
and it has 85% nutritional score. The usual advice is that if the food is suiting the dog there should be no reason to change. However, if you prefer not to use grain free food you can leave that box unticked in the filter section of the Dog Food Directory. Look for products that contain brown rice as it has better nutritional content. Some of the cold pressed foods are based on brown rice (usually about one third of the recipe) and might be worth looking at. We have a thread about these here.
Regarding the behaviour problems, you don’t say what they are or whether your Labrador is field or show type or whether you are a first time owner. I know a little about Labradors and they can be a handful at this age. Sometimes genetics play a part. What they need more than anything is training because it allows them to use their brain and energy. They also need clear boundaries. The more you put into this the better behaved the dog will be. If you haven’t already done so, consulting a behaviourist or attending a training club might be useful. Also, if you can find a Labrador forum on the Internet, the members might be able to advise.