When you change the screen resolution, what does that do overall?
Since I've an older (Late 2012 Mini i7 quad) running its original OS X 10.9(.5)
and a 20-inch aluminum Apple Cinema display, the native resolution is small
items on a large expanse. Settings in the 'system preferences' may help you.
The default screen resolution should be like a wide-angle effect with large field.
If somehow it seems oddly out of place, contact the seller; see if another of
the same model build year has the same appearance.
{If you just bought the unit, and did so from an official Apple Store, you have
14-days to make up your mind to return it. Contact them before the 14-days...
but if you bought from an independent authorized reseller, they don't follow the
official Apple Store (+online Apple) courtesy, but may work w/ you on exchange.}
The system-wide preference settings, including 'accessibility' are your choices.
In applications, such as a browser, settings do not usually affect the main window
where Finder and the user desktop live.
Good luck in this matter! 🙂