Line Width Does Not Show

In printing: 1mm line width is 1mm when printed, with ink on true paper, regardless of papersize and drawing scale, like in old handmade times, that's ok and works.
In drawing mode: my further trials have shown that on screen line width always is in scale 1:1.
For example if your unit is mm and the line width is 0.5 mm, zoom in until the line appears thick enough and measure it with snap off, it will say 0.5 units. If your unit is meter, it will say 0.0005 units.
In a mechanical engineering drawing, where a scale of 1:1 might be usual, there is less of a problem. In an architectural drawing which may depict a house of let's say 10 times 12 meters, the line width will appear much too tiny on screen.

So far my tonight's investigations

dellus  

I want to emphasize that version 8.0.2 is capable of doing what I want with line widths, because I did it with this version on the first project.

I just went back and loaded the first project into 8.0.2 and it shows the lines with proper widths (fat lines). If I draw a new line, it displays the line with the proper width (after I change the attributes to fat).

If I click New and draw a line, the new drawing is NOT displayed with the correct widths.

I tried to copy a fat line from the first project into the new drawing, but apparently this is not possible. Although I get the vertical and horizontal axis lines tracking the pointer in the new drawing when I select Paste, nothing appears when I click with the mouse.

I have found the solution to my problem.

I went back and forth between my first project (Proj 1) which shows both thin and fat lines and the New drawing which showed only thin lines, comparing the preferences.

First, I compared the Application Preferences: they were the same.
Next, I compared the Current Drawing Preferences: there were differences.

Drawing Preferences->Paper   Proj 1: Letter          New: Custom
Drawing Preferences->Units    Proj 1: Millimeter    New: Meter

I changed Custom to Letter and Meter to Millimeter.

Now I can see both fat and thin lines in the New drawing.

I'm surprised that the Current Drawing Preferences were carried forward into the New drawing given that they are called Current.

I changed these 2 settings based on a post I read that resolved a problem I had. Unfortunately, I don't recall what the problem was but I believe it had to do with printing my first project.

Thanks to everyone for your efforts.