Scope changes can come from multiple avenues in the project and they are expected. Similar to how you wouldn’t make a critical life changing decision, such as marriage, without knowing a lot about the person, project scope changes decisions should not be taken lightly. Actually non of the project scope management processes should be taken lightly. Research on the scope changes and then make the decision. You’ll be surprised in what you'll find. Uncontolled scope changes and controlled can lead to regression errors. Therefore, your risk register must be updated with the risk response strategy. Project scope management does not exist in isolation of the other project management processes!
Let's take a scope management example. Suppose your client wants the application to be compatible with at least four browsers. Initially, the client wanted it to be compatible with only one browser. You might be tempted to think, that’s easy. A few lines of code and we should be set. However, did you account for the testing that is required? It’s four times as much, since the application will need to be tested on each browser. Similarly, they’ll be other activities that’ll crop up. The project critical path may also change.
Best Practice: Using Lean Thinking and Agile Scope Prioritization practices also helps in managing scope creep (uncontrolled scope changes) in project scope management.