Pixel AR should be 1.0 Your height of the full frame (in your preview) should be 2 x 1080 or 2160 and the width should be 1 x 1920 or 1920. That would make a rectangle that is 1920 units wide by 2160 tall. The two images need to be one above the other.
But do not change the Project properties as your output frame in the final viewing is still 1080 x 1920 PAR is still 1.0
It appears to me you do not fully understand what the edit software is doing in your setup. You do not understand what each setting is doing for preview and what it does and is needed for output. What you see in your preview window is NOT what you will get in output. What you set in the project Properties is the pixels you get in your output. The stereoscopic 3D setting is the 3D format. Still confused?
You set the 3D stereoscopic to Top Bottom Full in the File/ Properties and then in the Preview window, right click and select video preview and set that to top / bottom full just to show the size of the frame as it is saved in the file.
Further to clarify- when I said the frame size will be 2160 x 1920, I did not mean to imply you change the project to that pixel ratio, just that is what you will get when you select Top Bottom Full.
However, in the render as
, you do
select a frame size as 2160 vertical by 1920 horizontal Top Bottom Full 1.0 PAR. This will not change the preview window.