Forget saving anything in the native OpenOffice or LibreOffice formats. Its a waste of time. Change the defaults to automatically save as .xls and .doc. This can be done from Tools\Options. Expand Load/Save and click General. The option to change the saved document type is at the bottom of the dialog box.
Unless you are doing complicated formulas in spreadsheets and macros in word processing, the documents will open perfectly fine in Excel and Word if you have a need to share them with others. I've been using OpenOffice & LibreOffice for years. I would never go back. Why pay MS for a lot of fluff that only a handful of people will ever need?