Thanks Constantin.
When I click the "Spot Slope" of Annotations, to add the slopes to the model, I get the arrows with units like 0.18, 0.2, etc., which are units that are not what we use here (Here we use inches/feet). The Project Units, of the Manage tab, say that the Slopes are 17 1/4" / 12" which is correctly stated there, but I wonder why on the drawing of the roof plan I get the 0.18, 0.2, etc., rather than the 1/4" / 12" units. Why is that?
Thanks again.
PS: I clicked on one of the symbols (0.18) on the roof plan, and then the Edit Type in Properties, then in the Type Properties dialog there is a line named "Units Format" and when I changed the content to 17 3/8" / 12" then all the slope numbers came correctly shown on the roof plan.
Now I wonder why this detour when that could have done, to begin with, in the Project Units dialog. It feels like the "Project Units" dialog is not the ultimate way to set the default units and we have to go elsewhere to finalize them, like in this case.