The project manager should review the 'issue register' to know what modifications have been proposed to an approved product during the stage. The issue register records all issues that may impact the project, including requests for change, concerns, and off-specifications, providing an overview of current and potential problems affecting project products. References: PRINCE2 Foundation training materials and issue management guidance.

Change management is defined as the means by which an organization transitions from its current state to the target state. It encompasses all activities involved in managing change, including handling changes to the scope of projects and ensuring that changes are implemented smoothly and sustainably. This involves strategic planning, oversight, and ensuring that changes are accepted and adopted by all stakeholders.
References: PRINCE2 Foundation training materials and glossary.

Uncertainty in a project is identified, assessed, and controlled by applying the risk practice. This practice involves systematic risk identification, analysis, and management, ensuring that risks are properly understood and addressed through appropriate responses to protect the project objectives. References: PRINCE2 Foundation official guide and risk management section.

In PRINCE2, a risk is defined as any uncertain event or set of events that, if it occurs, will have an impact on the achievement of project objectives. This definition emphasizes the uncertainty and potential effect on objectives, rather than the certainty or immediate occurrence of an event. References: PRINCE2 Foundation Training Manual; PRINCE2 2017 Foundation handbook.

The 'Implement' step within the recommended risk management procedure in PRINCE2 involves taking planned actions to respond to a risk. This step is crucial as it moves the risk response from the planning stage into actual execution, thus addressing the risk directly to mitigate its impact on the project.References:
PRINCE2 7 Foundation study guide and official documents.