Stop talking to your dog like they understand you.
Our dogs have no understanding of our language, and so the things we say to them are merely perceived as sounds. If you want your dog to understand the meaning of a particular sound, you have to associate that sound with a behaviour, item, or outcome over many repetitions before they will understand the connection. And if you say the same word but change the tone of your voice and the sound no longer seems the same to them, they are very unlikely to understand you. This is why clicker training can be so powerful – the clicker is a guaranteed way to make sure the sound stays the same no matter the handler’s emotional state or even if the dog is being handled by someone completely different.
Too many people say things to their dogs like, “no don’t do that!” or “remember to be nice” or “what did I just say?!” – your dog understands none of this. Instead of saying sounds at them that mean nothing and only add to the stress and frustration of a situation, try simply using a single command or a marker they do understand. This will give them useful information and likely lead to a better outcome in the situation.
