To create a submenu from existing buttons:
Open the menu that contains the buttons you want to move.
Select one or more buttons that you want to move to a submenu.
Select buttons by clicking them once. To select more than one button, hold down the Shift key as you click.
Choose Project > “New Menu from Selection.”
The selected buttons disappear from the current menu, and a new My Submenu button, which links to the newly created submenu, appears. This new button has the same style as the default buttons that come with the theme you are using, but you can change its appearance if you want.
Click the new submenu button once to highlight the text, and type a new name if necessary.
An in-place control (shown below) appears below the button. Use its controls to select a new typeface, font style, and font size from the pop-up menus if you want.