You may also want to check the drawing location from the face, it is at the top. Basically you can have the joists start from the top down when drawing or the bottom up.
I understand a lot of people are used to drawing top down, plan views in 2d view, especially when doing joist layouts. That is no problem, simply click the structure tab. It is easy to create joist layouts in PlusSpec and add in the associated trimming beams or annotations.
I’ll make a video if it is of assistance?