Ok that link has baffled me even further, I have been trying to understand this for months now!

All I want to do is print any picture in as much quality as possible on my printer which is a very nice 8 ink canon with A3 capability.

My understanding is set size of image  to 4950 x 7020 and don't move the default setting of 72 dpi/ppi thing at all. 

I will then be able to print my image on A3 with no quality loss/resizing etc?

This image will automatically now print at 300 dpi ( dots per inch ) and it does not matter that i didn't move the default 72 to 300.

Am I right >?