There's something I really can't fathom about print sizes. I have a Canon Pro-1 and, using fine art matte paper, the driver sets a minimum of 35mm borders all round. So I've set up a Job Profile that uses this driver setting (Fine Art) and the paper size is set at A3+ (330x485mm). By default I get "Original Size" in the preview window.
It's just like you built a boat in your basement, and now you can't get it outside.
Open the Qimage HELP FILE and reset Printer.
Now click on Print Page setup (Upper right corner where there are 3 buttons; the left of the three)
Set the paper type and size. Set Quality, and set color controls to off (Assuming you use a printer profile)
Close that Printer page setup (The driver)
Now Qimage will show you the printable area of the A3 page. 411.9mm x 290.1mm
That's what your printer allows for maximum print size on A3.
Now, what size print do you want?
Forget original size. We can deal with when one would need that later.
Assuming you want the largest print possible, you open Print properties, Crop scissor on, and click Fit to page.
Ok, let's stop here and see if you are up to speed, and you can tell me what EXACTLY you want to make.
Fred