If using Libre Office it might be a good idea to save documents as Microsoft Office documents. Therefore if you need to email these files away or work on these files on another computer then you know they will open Okay.
By default Libre Office (& Open Office) save word processor files as .odf (Open Document Format). You can save files as you go by simply clicking “Save As” from the “File” dropdown. However if you would like Libre Office to always save files as Microsoft Word compatible .docx files, here are the simple steps to do this.
Step 01: Open Libre Office using the main shortcut on your desktop. From the initial splash screen click on Tools / Options
Step 02: Under the Load / Save / General section, change the save type for “Text Document” to docx (it will say Microsoft Word 2007/2010/2013 XML)
Repeat for Spreadsheet changing to .xlsx file type. To do that click on the dropdown that says Text Document and change to Spreadsheet.
This time look for Micrisoft Excel 2007/2010/2013 XML. Click OK to apply and from now on when you save a file in Libre Office it will be fully compatible with Microsoft Office.
Test these by saving a blank Word file and a blank Spreadsheet. Depending on your operating system you may have to right-click the saved files and “Open With” and choose the default program (being Libre Office).