To view the test case references, click the check box next to the test case and click References.
A popup will open which shows where this test case was used in Execution Sets or Load Tests as below. For more information about Execution Sets or Load Tests, please navigate to their pages or click here for Execution Sets or here for Load Tests.
Alternatively, while the test case is open, you can click "More options" and choose "Show References":
Tip
Clicking on the Execution Set or Load Test title in the image above navigates you to the Execution Set/Load Test settings where you can edit and save any changes there.