In PRINCE2, the role responsible for appointing the Senior User, as well as other key project roles such as the Executive and the Senior Supplier, is typically taken by someone from corporate or program management, or the customer. This aligns with the principle of clearly defined roles and responsibilities, ensuring that the project has clear governance and accountability. The Senior User is appointed to represent the interests of all those who will use the project's products, who will benefit from the outcomes, and those whose work might be impacted by the change.
PRINCE2 Foundation Manual

A minimum requirement for applying the quality theme in PRINCE2 is keeping a record of all planned quality management activities. This requirement ensures that there is clear documentation of what quality checks will occur, who will perform them, and how they will be executed, which is fundamental for maintaining control over quality assurance throughout the project. References: PRINCE2 Foundation Handbook, Quality Theme section.

In a programme environment, there might be multiple business cases within a single project, each supporting different parts of the programme's overall goals. This scenario is common when a project is designed to deliver outputs that contribute to several overlapping strategies or objectives within the programme.
References: PRINCE2 Foundation Handbook, Business Case Theme section.

The Project Manager should review the Highlight Report to report to the Project Board on the status of the project's issues. The Highlight Report provides a regular summary of the stage status, including progress against the plan and details about any issues or risks, making it the appropriate management product for communicating current issues to the Project Board.
(PRINCE2 7 Foundation Handbook, AXELOS)

When a project manager plans to keep the CO2 emissions of the project aligned with the business strategy, this addresses 'benefits sustainability'. This aspect involves ensuring that the project's outcomes and benefits are sustainable and align with broader business strategies, such as environmental objectives and corporate responsibility goals.
PRINCE2 7 Foundation documentation on sustainability in project management.