When I use asterisks, that is *, LibreOffice removes them and replaces them by bold text.
Typing an asterisk [*] before and after one or several words makes them bold without needing to use the mouse. In the same way, an underline character [ _ ] before and after one or several words makes them underlined.
To remove this behavior:
- select ▸ ▸ ▸ ;
- in the list, uncheck Automatic *bold*, /italic/, -strikeout- and _underline_; and
- click OK to apply the changes.
To learn more about automatics, please read this FAQ item 025 – These automatics annoy me!.