To the left of the query area are the navigation buttons. The navigation buttons allow you to browse through your query history so that you can review and re-execute a previously executed query. The query history is available through the object browser.
Clicking the Go Back button loads the previous query in your history, whereas the Go Next button loads the following query. Only queries that execute without errors are added to your history.
As you navigate with the Next and Go Back buttons, the queries you navigate through are not executed unless you explicitly execute them by clicking the Execute button. The Refresh button re-executes the last executed query, which may or may not be the current query in the query area.