Change the font size using the options in the Display menu in Windows and in System Preferences in OS X. Though changing the font size affects the text across the operating system, it may not affect the text in browsers. Use the zoom options in your default browser to enlarge or shrink the text.Continue Reading
In Windows 7, click the Start button, and type "font size" in the search field. Press Enter. In Windows 8, swipe in from the right side of the screen or move your mouse to the upper right of the screen. Press or click Search, and type "Display" in the text field. On OS X, open the Apple menu, and select System Preferences. Next, select Universal Access.
In Windows 7 and 8, choose the new font size in the Display window, or click the link in the left pane to select a custom size. In OS X, locate the Zoom section in the Seeing tab. Select On to enable the zoom feature. Hold down the Command and Alt keys, and press the + or - keys to change the font size.
In Windows, click the Apply button, log off and log back in to see the affected changes. You do not have to relog on a Mac.