Dogs can learn very quickly that us using certain words or actions means we want them to do something in particular. However, they do not come to us pre-programmed with these behaviours, they have to learn them.
Sometimes I get asked what is the word to make my dog do this or that. The answer is simply: the word can be whatever you want, as long as you teach the dog what you expect them to do when you give them that cue.
It is important to realise that, no matter how many times you shout ‘roll over’ at your dog, or in how many different tones of voice, or volume levels, the dog is not going to roll over unless you’ve taught it to. The same goes for ‘sit’ ‘lie down’ ‘come back’ ‘on your bed’ and any other behaviour you want your dog to do.
Think of it this way. If someone shouted ¡Sientate! at you over and over again, unless you speak Spanish, you would have no idea what to do. (It means ‘sit down’ by the way)
Don't get annoyed at your dog for not doing what you ask, chances are they may not know what it is you want. Put in the time to teach them consistent cues and behaviours. Then you will both have more fun and understanding of each other.