Page size and margins

So I am trying to set my own default A4 page in Write. It correctly sets my A4 page at 21cm x 29.7cm. But even if I reduce all margins to 0 it puts its own 2cm margin around the page. How can I get rid of that to set my own true margins?

Version of Libre and your OS please? It works for me, just persevere.

LibreOffice (x64) / Windows 10

Try adding -2cm or Try with A5 page and give them the alignment of 21cm x 29.7cm