"You are a senior engineer" changes how sure the answer sounds, not how right it is

Role prompts, such as "act as a senior engineer" or "you are an expert copywriter," influence how AI models present information rather than the accuracy of the content. These prompts lead to more assertive answers, increased jargon, and fewer hedges, making the responses sound more confident. The core question remains whether such role prompts genuinely alter the model's knowledge or merely its presentation style, as suggested by the observation that they change how sure an answer sounds, not how right it is.