Here are a couple of ways to make text on your iPhone, iPad, or iPod Touch more readable. If you’ve upgrade your device to iOS 7, which Apple introduced in the fall of 2013, you can turn on Larger Type and/or Bold Text.
To turn on either of these options, start by tapping on the Settings app. Then, tap General and then Accessibility. The Zoom and Larger Type options are menu items whose switches can be toggled once you tap on the option. Bold Text allows you to slide its slider to the On position in the Accessibility screen. Note, if you turn on Bold, you will be prompted that your device will need to restart. An article at 9to5 Mac provides more details about how to enable and use these features.