Enter or Paragraph and Indentation

Hello all,
I am writing a (quantum) physics book with TexMacs. I am using the document style "tmbook" and everything is going very well so far and it is very beautiful.
Two questions though.
• When I press "enter" it gives me a new paragraph with an indentation and a distance between paragraphs. However I think I should use the "Paragraph" command instead to introduce a new paragraph, each time, to have a better structured document. Is this the right way to do it even if it is a bit longer than pressing the "Enter" key?
• In Document/Paragraph/First indentation (or in Format/Paragraph/First indentation) when I change the value of First indentation, nothing happens. I thought it could be because the tmbook style overrides manual commands but I have tried all book formats and others and it still does not work. I searched on the internet in The Jolly Writer, the Manual, The Reference guide… I assume it is simple but I can’t find it. Can someone give me some clues?
I use TexMacs 2.1.4 on Intel MacBook Pro, MacOs 14.6.1
Thank you VERY much.
Normand