Go on Dashboard and you will find Online store on the left navigation bar, click on that > choose menu > Now you will be on the menu panel where you can choose menu position according to your requirement which you want to edit > click the button below to customize to edit selected one > in the panel you can edit the menu list going through the menu structure. you will find the edit button of each menu name and also find an arrow to adjust the position. After edit, the menu > click on the save button.