I’m using a bold heading style.
When I save it as docx, all of bold heading style is changed to normal font style.
Saving the product of any application in a format other than its own native format will often lead to loss of formatting. When using LibreOffice, save your work in native LO formats (.odt, .ods, etc). Only export in .docx format when necessary to share with others. Same goes for Microsoft, WordPerfect, AlphaFive, LaTex, Scribus, and probably others.
How do you flag your heading? Do you assign it a specific paragraph style such as Heading 1? How do you make the heading bold? Modifying the paragraph style? Using a character style? Adding bold with a tool bar button or Ctrl+B (manual formatting)?
i;m using custom default heading style with bold font.
“Custom default”? This is a bit contradictory. Factory Heading 1 + bold manually added? Anyway, it should be kept after closing and re-opening. Attach a 1-page sample file with the problem still present. To do that, edit your question and use the paperclip tool (tool not available with comment).
It could be a compatibility problem between Word and Writer.
Basically:
Always create and save your files in LibreOffice and save them in ODF format (ODT, ODS, etc.).
Always keep these files as their source. If you need other formats for distribution to partners, you can open an ODF file and save and distribute another format with ″ Save as… ″.
This way, you always have working files available in your system environment.
See:
https://wiki.documentfoundation.org/Faq/General/118#Edit_different_file_formats_in_LibreOffice
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Please report the behavior as a bug in Bugzilla .
See also: How to Report Bugs in LibreOffice
Please announce the link from the bug here.
To do this, edit your initial question. Thank you.