Like all AI devices that use National Language Processing or NLP, Alexa does not understand all voices easily. But she learns to understand her people over time. She does, however, require people to speak in simple terms, with appropriate pauses, and use specific word orders. There are many times when she will say "I'm sorry, I don't know the answer to that question." More than likely, she doesn't recognize a word order or misunderstood the question.
Note: Your Flash Briefing settings apply to all Alexa devices registered to your Amazon account, and all users in your home get access to the same Flash Briefing content. However, if you or anyone in your home has a voice profile, Flash Briefing automatically skips stories and news items you've already heard. To learn more, go to About Alexa Voice Profiles.