Always "Manual execution" in execution overview and report: how can I change this value?

I don't remember seeing this anywhere as something that can be configured so I can only hazard a guess that it's a value set by the system depending on the method of execution, e.g. a person executes a test using the Test Player (Manual), or a test execution is posted via the API (Automated).

For a definitive answer you could try contacting SmartBear support here: SmartBear Support