Have a bit of a problem. I'm trying to adjust the resolution on a 2013 27" iMac. Brand new, bought on April 6 2013 from Apple. My friend is 84 years old so, I'm trying to help him adjust the screen so he can see the screen. Any direction would be great.

You can select "scaled" in the Display tab of the Displays system preference and get a selection of resolutions. LCD displays go a bit fuzzy, though, when run at lower than their native resolutions, so I'd suggest you leave the resolution at the native setting and try your friend with the Zoom feature you'll find in the Accessibility system preferences. That may work better for him.

Regards.

The purchase date isn't the important info here. The actual model of the iMac is and this info is in the model identifier. For example, I have a late-2012 iMac, model identifier is iMac 13,2. I will add that there is no 2013 model available. The most recent at this time is the late-2012 model which I have.

On my display if I select Apple->System Preferences->Displays then press the button "Display" I am presented with a screen which shows Resolution and Scaled as button options. "Best for built-in display" is the default, however, clicking on "Scaled" brings up the various resolutions that can be used with the display:

From this I can select a display with larger items, but keep in mind that while a larger image can be selected (using a smaller width x height value) it will not be as crisp and sharp as the default.