Final answer:
Using short-term gains to advocate for changes is part of the controlling step in management, which affirm the effectiveness of an organization's control processes.
Step-by-step explanation:
In the principles of management, using the credibility of short-term gains to advocate for further changes is primarily involved in the controlling step. After planning, organizing, and leading, control is the process by which an organization ensures that activities are completed as planned. By highlighting short-term gains, managers can support the effectiveness of their control methods, thereby fostering trust and motivating stakeholders to support further changes and initiatives.