How to Change Scale in a Designed Architecture Floor Draw?

I am a Civil Engineer a little bit interested in using LibreCAD in my project office and I started some tests of the software trying to design just a complete bathroom (in architecture floor plant). So, after some initial disappointment with the "User Manual" about how to put dimensions in the lines (or "line entities"), the test was going on very well till I didn't find in the (very poor) LibreCAD "User Manual" how to change drawing scale (not printing scale) in a draw of a floor plant. In my floor plant draw (with a external wall rectangle of 200 cm x 400 cm) I used 1 (one) unit of screen grid for each 20 centimeters, but when I call for the dimensions numbers pressing the button "Draft" appeared "160" in the wall that was expected to be "400". I tried to modify scale ratio in every tool I supposed to be up to this change, but unsuccessfully. I am suggesting now that the "User Manual" team insert a new chapter entirely dedicated to lear the users how to deal with drawing scales "in the real world", simulating real world design with architecture draws such as the example of my LibreCAD test! In sum, it is important the "User Manual" be written by the authors with a team of engineers driving them with "real world" drawing examples.

It took me a while to understand what you mean with drawing scale (vs printing scale). So you want to use the screen grid to determine lengths. Out of the box the grid scaling varies dynamically to zoom ratio.
If you want a fixed grid size you have to set it at Options - Current Drawing Preferences - Grid. Assuming you have set units as Centimeter X-Spacing and Y-Spacing then have to be 20.
Using the grid to determine lengths is recommendable for occasional amateurs only. Professionals use input at the command line. More to learn.
I was not amused by the unfriendly words in your other posting, especially the last one.
We can be glad to have a manual like that at all, long time we didn't. If you had studied it properly you would have seen it tells about the grid settings and the Draft mode.

Dear Dellus,
It's really boring to read what you arrogantly wrote me not accepting well cripticism about the quality of the LibreCAD's User Manual. Sorry, I am a professional, not a student who has a lot of time to learn how to operate a software without a professional (or something like this) manual, and because of this reduced time to learn I would like to have a book, or a complete "User Manual" to learn how to use LibreCAD professionally. In my country some years ago an enthusiastic government authority gave up to politically support Open Source (OS) software in agencies as a public policy when discovered OS softwares generally have poor documentation, a problem that OS organizations around the world must dedicate itself to solve, under the penalty of OS software continue to be just for geeks (I sincerely hope this ultimate word do not mess with your pride again)!

E. A. Caputano,

I have read both posts, yours and dellus'. I don't see any arrogance in dellus' posts.
He is a very valued supporter, not only in the forum, who sacrifices his free time for it, like everyone involved in LibreCAD.

He rightly criticized your choice of words in your other post, in a friendly tone.
https://forum.librecad.org/Only-a-box-appears-when-entering-text-tp5722083p5722487.html
Even if we don't have a designated code of conduct, the rules of general politeness and friendly interaction still apply.

The authors of the manual were not paid at all, just like the many developers of the software were never paid and also the supporters here.
I can't tell how many people have put countless hours into the software, documentation, and support.
This is the way free software communities work.
And there are many people who are happy to have LibreCAD and who appreciate the work of the volunteer contributors.

LibreCAD was never intended to be used in a professional environment.
Nevertheless, one hears again and again that people also use it commercially successfully.

Anyway, I gather from your post that you probably have a general problem with free software or have been disappointed more than once.
No one is forcing anyone to use free software.
If this model isn't right for you, you'll have to spend some money and pay someone, who in turn will pay people to professionally produce software and documentation.
If you are not satisfied then you may have the right to complain in this way.

So please pay attention to your choice of words in the future.
With a friendly question everyone got information and support here.

Armin