I've done this same job in the past. Sometimes when you initially do the setup for the headset you say the words differently to how you would naturally say them while you're working. In that case, try to stay back for a little bit or get in a little earlier and redo that setup process. Even if you ask your trainer tomorrow to redo it because it's having trouble recognising the commands, they'll give you a hand because they want things going as smoothly as possible. Our system had a fair few different commands, so personally I found that speaking a little softly at a comfortable level allowed me to maintain consistent fluency. It wasn't perfect by any means, but you can get caught out thinking you have to speak loudly because you're likely in a loud environment. Don't give up though. You can do this and you can make it work. Just keep trying your best and you'll build your comfort levels up with it.