My dad just asked me how to make all the text appear bigger his iMac and without thinking I sent him to the Accessibility options in Sys Pref but there was nothing to be found. To me it seemed common sense since the iPhone has a system-wide text size option but I can't find a similar thing for Yosemite. Any advice? I know I can make things like finder text bigger but that doesn't help when say, composing an email, or browsing the web (let's mark manually zooming in and out as a poor solution also).
You can use the Accessibility->Zoom feature to make things appear larger. Default settings can quickly make you dizzy though, as the display moves around, following the mouse. Clicking the Options button brings up a dialog that lets you set min and max zoom, and also set it so the screen image moves only when the mouse pointer reaches an edge. That's a far less vertiginous option.
27inch iMac and a resolution change isn't a suitable solution I feel. The zoom feature is useful but again not ideal - I don't understand why there isn't a text size option like on iDevices, the mind baffles. Thanks for the suggestions so far!
I think the Yosemite font size is small. It should be an option to increase the size, not everybody are 20/20
the only other thing I can suggest is maybe try tinkertool. http://www.bresink.com/osx/0TinkerTool/details.html