A typical parenting challenge that causes many parents frustration can be expressed in the following question: "What do you do when you want your child to do something, and he responds with: 'I don't care', or 'I can do whatever I want to do', or 'I am not going to my room', or 'try to catch me', or 'I won't eat this, you can't make me'"?
When talking to your child is very hard and makes you almost (or sometimes) lose your temper, when your child simply won't do what you ask of him, you feel tempted to blame your child. But this just keeps you feeling like a victim. Where you need to focus is on what you are doing to cause what is happening to you. Take responsibility for your results, pay more attention, and you will begin to see small changes that you can make for the improved results that you want.
The first thing to focus on when you want to improve a child's behavior is on the improvement of your own behavior. Pay particular attention to ways that you speak to and around your child. Children are programmed by nature to behave in the ways that people behave around them.
If you sound harsh, impatient, disrespectful, cruel or cutting in your speech toward or around your child, you literally program your child to speak similarly. So begin by paying more attention to the ways that you express yourself, and bring more calm consideration and compassion into your tone.
Next, observe how you react to your child's behavior. Do you blame your child for the unpleasant ways that you react to his behavior? This makes your child responsible for your behavior; but in fact, you are responsible for that. As you take responsibility for the quality of your reactions, your example teaches your child to take more responsibility for the quality of his reactions to you.
If your child can "make" you lose your patience, feel disrespected, become frustrated, or feel like lashing out hurtfully, your child is actually the one in charge. You begin gaining control when you first demonstrate self-control. Practice remaining calm, confident and loving NO MATTER HOW HE BEHAVES. From that calm place, you can decide what you need to do and do it more effectively.
What he is doing is actually a form of testing you, to see if you your love for him is deep and secure enough to maintain your loving connection with him even when he behaves improperly. If you can pass this "test" he will feel more secure, more loving, more appreciative toward you, and that motivates him to try harder to cooperate with you and please you.
Also monitor the degree of anger and stress in the household. A stressful atmosphere causes children to feel so aggressive they cannot even control themselves when they want to.
Also look at the quality of relationships going on around your child. If he sees much strife and contention, he is led to relate similarly.
Now that he is six, you can have a conversation with your child when there is peace between you, explaining how you want to be spoken to, and why. Ask him gently why he has been speaking to you like that, and if there is anything he needs from you to help him to stop. Don't turn this into an argument. Model excellent listening.
In this conversation, do not sound critical or convey a superior attitude like "I am right and you are wrong." You might even admit that you have the same problem (all of us do), and talk about the kinds of trouble your disrespectful or inconsiderate speech has caused you (you might also include how you talk to yourself when you feel mad at yourself).
Finally, if you can maintain your loving peace and poise in response to this behavior of his, you can warn him that he will lose a privilege of some kind if he does not change his manner of speaking to you right now. Explain the reason for this, such as: "In life, when we speak disrespectfully to others, we lose their support and cooperation. My removing a privilege in response to that behavior prepares you for the real world, and that is part of my job."
However, warnings and consequences will NEVER work if he is too exposed to negative modeling, if his behavior causes your angry reaction to override your loving connection, and if no one really listens to him when he expresses himself in more considerate ways.
In sum, pay closer attention to your behavior to see how you may be provoking what you do not want from your child, and to find ways of improving your own behavior for better results. This models for your child the application of a higher level of self-control. Indeed, child discipline really does begin with better adult self-discipline.