Set up your document with the dimensions you want the pages to be when they are exported. So if you want the exported content to be 1920 x 1080, then set that as the dimensions. Based on the screenshot, it looks like you would want a shorter page.
With the Slider Page Formats, you can make the pages different sizes if they aren't all as short as the one in the screenshot above. In InDesign, select the Page Tool and Alt (Windows) / Option (macOS) drag an edge to change the page size.