A Quick Save is enabled once a query has been previously saved. The Ctrl+S and options both activate a Quick Save.
During a Quick Save, you are not prompted to select a file name if that Query tab has already been saved before.
However, using the Save As menu always prompts you for a file name. If you have not saved the Query tab before (or have clicked since the last Save), you are prompted for a file name even if you click or press Ctrl+S.