Set readable captions on an iPhone
Choose captions for the current programme, then adjust text and background styling under Accessibility if the app supports system styles.
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Choose the track first
Start a programme known to offer captions and open its playback controls. Select a caption track there. A language subtitle track may omit sound descriptions. A closed-caption or SDH track usually includes additional cues when the programme supplies them. If no tracks appear, use another title in the same app before adjusting the phone’s system preferences.
Change the style on a programme you can repeat
On iPhone, open Settings, Accessibility, then Subtitles & Captioning. Choose a larger style or customise the background and text for your needs. Return to the same scene and check whether the app follows that style. Some players use their own caption preferences. If the system change works in Apple’s player but another app keeps its original appearance, look for the other app’s own caption settings.