When editing a specific page - you can change the page layout in a couple of places, using the grey tabs at the top of the editor. LAYOUT best tab to choose, but if you're already on the HELP tab, changing the layout is one of the options available as well
ABOVE - A Drag and Drop editor window with the HELP and LAYOUT tabs indicated.
To change the page layout, select Web Pages, then the More Options cog next to the required page. Then select the Change the Page Layout button to reveal these options:
ABOVE - Example page layout types available. Available page types change depending on the existing page type.
You can see your current page layout listed above in this screenshot example.