To customize the paper size, orientation and the margins, open the Layout Settings, next to the print button.
On our desktop web app, this is usually located on the right of your screen, or in the “Document” toolbar. On our mobile app, click on the edit button on the top of your screen.
Under the Pages settings, you can now edit the Orientation of the paper, the Page size and the different margins.
If you are in the US, the default page size is US Letter and the sizes are in inches. In all other countries, the default page size is A4 and the sizes in mm/cm.
By default, Flat will add pages numbers if your scores contain at least two pages. You can force displaying the pages numbers on all the pages and choose the first number to use in the page settings: