thanks for help. first of all, I must have updated it due to incompatibility between nvda report addon and nvda screen reader, because, she has got very, very old version of nvda. She told me, it was 2013.x.
I will try both your suggestions even I thought that object navigation is automatically activated. Also I will try to search for possible updates of office. Is there any setting in outlook which should be also changed for better performance?
again, thanks for all your help.