Trouble Editing Menus

Can anyone help with this issue – I’m a photographer trying to set up a website but I can’t create sub menus, I can create the page, upload images to make a “gallery” page. In the appearance screen I can go to “menus” and load them in under a parent page titled “galleries” I can indent each page to the right and even change the order to create “parent and child” pages the way I want them to appear, BUT when I click “save menu” all my changes go back to a single list eliminating the sub menu aspect so that it appears like a string of individual pages on my site. I have designated the parent page when setting up each page so that is not the issue. HELP kenmoranphotography.com