How to increase numbering in sections in LyX

If you want more than just three levels of numbering within sections, you can achieve that with two different approaches inside LyX.

1. By changing Document’s settings

Document -> Settings -> Numbering & TOC

2. By applying LaTeX commands

\setcounter{secnumdepth}{5}
\setcounter{tocdepth}{5}

First approach is more elegant in case of LyX, as you will see the numbering within LyX document. In case of second approach, you will see it after compiling the source.