If you have unchecked "Resize to Fit", then Resolution does not have any effect.
Even if you check "Resize to Fit", it has no effect in some situations.
As far as exporting goes, the resolution setting has no impact on the quality of the image. Regardless of what you enter into that box, the image will have the same number of pixels. That is true whether you specify pixel dimensions or not.
Nice one!! Thanks for that.