Unicode displaying trouble in LO

Hi there,
I’m from Vietnam and my langue use UTF-8 unicode for some special chars.
Within Layout, the autocorrect function did transform some chars like this:
Õ → Ơ ; È —> Č, etc…
(Only Arial Narrow font wasn’t changed)
When i used Text or Label to type, if it happens, i press Ctrl-Z and it solved.
But it always be in Autotexts or infomations from Sketchup model like Component’s Description.
I think if we can disable the spell-check and auto correct, my problem will be over.
So, can anyone help me, please?
Thanks a lot.
(sorry for my english) Here’s link to sketchucation topic, there’s an image of this problem.
http://sketchucation.com/forums/viewtopic.php?f=12&t=63918&sid=2e91fc74c9bf48d7627ae3c143b17851
Thanks again