I visited a website that had templates for brochures and I clicked on one, and suddenly the default document size shown for word processing in Libre Office on my computer changed from 8 1/2 x 11 to a much smaller size. I need to use the default size. I have looked everywhere in the menus and can’t find a way to change the size back to default. Can someone help me? Thank you.
Try in the menu Format>Page....
Then in the dialog box “Page Style: Default Style” click the tab Page.
Choose your Paper Format and click OK.