Formatted text at every opening of OpenOffice

Here is the translation: Well, here’s a small annoying problem with OpenOffice. I keep modifying the styles, saving everything, but each time I open an OpenOffice document, it’s in preformatted text. I have to select everything and set it to Default Style at every opening.
I even tried changing the style of the preformatted text, but nothing works—when I close the software, it’s as if I hadn’t done anything.
My version is up to date; I installed it recently.

Thanks in advance