Well, I'm confused by your problem -
I've been using LO since it was OO; merely using 'save as' when
I'm finished writing for the moment, then when I re-open it, I just start
writing again.
Are you perchance, plopping some text - written in another style -
into the document?;
if so, then that document's style will retain it's formatting
unless you first place it into a non-formattable document, as notepad.
If you're plopping other text into the document, then this is not a
bug;
it's designed in order to allow indentions, etc. within the
framework of the document - a nice touch which I like re. LO
If you're not plopping other text into the document, then I still
haven't a clue