Every time I create a header and footer format in a writer document I press apply then ok, but when I open the saved document the underline in the header and footer are gone and I have to redo that part of the formatting.
The same problem has happened in previous versions of Libre Office Writer. Is there something I am doing wrong, or not doing, or is it the software?
What filetype are you using?
Which version of the LO are you using?
Can you upload an .odt type sample file here?
The file is saved as a Word 2007 .docx
Libre Office Version 24.2.1.2
Air Fryer - Sausages.docx (10.9 KB)
What is the “underline in the header”? Word underlining? Bottom header border?
If this is a personal document, save as .odt. Saving as .docx causes conversion when opening the document and again when saving it. This has a cumulative damaging effect because ODF and DOCX formats are based on different principles which have not necessarily exact counterparts.
Additionally, your document is completely direct formatted which makes it difficult to tune. Note also that DOCX lacks the notion of character style, compelling you to direct format intra-paragraph “embellishments” (blod, italic, …).
Thanks for the quick replies to my question from Zizi64 and ajlittoz. If I understand you correctly (ajlittoz), if I save the documents as an ODF text document (which would result in the file extension .odt, then the formatting will be retained. However, if I save it as a “Word” document, then I would continue to lose some formatting, including the header/footer issue. Is this correct?
That is a likely outcome, yes. Whether it happens or not depends on your work habits and the nature of your document. We can’t say for sure that there will be degradation, only that is it not unlikely 
When saving to a “foreign” format, the translation is rarely perfect. Sometimes the loss in translation is visible, sometimes not. Writer has some functionality which is not possible to store in docx format, and the docx format supports some (Word) functionality which does not exist in Writer. Similarly, there will also be loss in translation when you use MS Word and odt format.
Thanks keme1 for your reply. What format do you recommend I save future documents in, because I do not want to have to re-format every time I open a saved document so that I can print it with the formatting I want?
For all apps, a work in progress is best saved in the format native to the app. For Writer, that is the “ODF text” format.
Depending on which version/translation of Writer you are using, that storage format will appear in the File type: field in the save dialog as some incarnation of “ODF text document (*.odt)” or “Writer document (*.odt)”
To ensure that your finished product does not change when shared with others, it may be better to use a copy saved as PDF for publishing, if that is a relevant situation. The PDF format is intended as a “stable version”/“immutable” and does not facilitate further editing, so keep your “work in progress” in the ODF format and only use pdf for the “published copy”.
When using any application, save in application-native format. Using Writer, save .odt.
You have not answered about the nature of your “underline”. IMHO, underlined words translate correctly to DOCX, but if you play with paragraph border or header area border, I am not sure how it translates (or not). I do think you’ll lose header area border because this notion is different in DOCX.
Thanks keme1, I will save future documents in that format. Thanks again for all responses. Much appreciated.
For information, I have just saved the Air Fryer - Sausages doc. in .odt, then re-opened it and the formatting for header/footer is still there.
Regarding the underlining, I went to the header and formatted it with an underline line, then did the dame with the footer. The reason I did this is because I wanted the entire width of the header/footer with a line across it.
That’s the way to do it. And it confirms it does not propagate to DOCX because DOCX has no notion of page style. It has “sections” which are totally different from Writer sections with are parts of pages. Don’t confuse one for the other.