Turn on subtitles or closed captioning
To use subtitles or closed captioning for the deaf or hard of hearing, follow these steps:
Go to Settings > General > Accessibility > Subtitles & Captioning. Then tap the switch next to Closed Captions + SDH.
Customize subtitles or captions
In iOS 7 and later, you can customize the style of the subtitles or captions to better suit your needs.
Go to Settings > General > Accessibility > Subtitles & Captioning > Style.
You can choose one of the predefinded styles like Default, Large Text, or Classic. To create your own style, select Create New Style.
You can also change the font, size, and color of the text along with the color and opacity of the background.
View new style
To view your new style in full screen, tap .
Tap Save, at the top of the window, when you're happy with the new style. This style will be the default style for subtitles and captions.