How to edit a style package?

I would like to change some parameters in the “book” style package in Texmacs, like the number of empty pages automatically inserted after a title or a part, or the way page numbers are displayed.

I figured I could edit or create my own style, inspired from the style book, but with my own modifications.

This link is supposed to help.
However, I cannot manage to save my file without an error !

Where should I save it ?
C:/Program Files (x86)/TeXmacs/packages/test_style.ts does not work…

I have the same saving problem when I just try to edit a pre-existing style file (when I click “edit the source code”) : it won’t save my modifications or appy them…

Dos someone know how to do ?
Thank you very much.

You can always put the style file in the same directory as the document.

What do you mean that does not work? It cannot find it? or you cannot save it there?

“Edit source code” does not work for me either sometimes. I should give a look at this problem.

Try this path: