A Power BI developer customizes dashboards by creating role-based access controls and designing visuals tailored to the needs of different user groups. For example, executives might require high-level KPIs, while analysts need detailed data views. Power BI developers can use Power BI’s Row-Level Security (RLS) to ensure that users see only the data relevant to their role. Additionally, they design interactive elements like filters and drill-downs that allow users to explore the data in ways that align with their specific responsibilities, ensuring that each user gets the most relevant and actionable insights.