YouTube’s default caption size is small, and on a phone or a TV across the room it can be genuinely hard to read. The setting exists on every platform, but it lives in a different place on each one — which is why it’s often hard to find.
On Desktop (Web Browser)
- Play any video and click the CC icon to turn captions on.
- Click the gear icon in the player.
- Select Subtitles/CC, then Options.
- Adjust Font size — you can also change font family, colour, background colour, and opacity here.
These settings persist across YouTube in that browser, so you only set them once. They don’t sync to other devices or browsers, though.
Keyboard shortcut: with captions on, pressing + increases size and − decreases it, without opening any menu.
On the Mobile App
- Tap your profile icon, then Settings.
- Select Captions.
- Adjust Text size and style.
On iOS, YouTube also respects the system-wide caption settings under Settings > Accessibility > Subtitles & Captioning, which applies across apps rather than just YouTube.
On Smart TVs and Streaming Devices
Here the caption size usually isn’t controlled inside YouTube at all — it comes from your device’s system accessibility settings. Look under Settings > Accessibility > Captions on most smart TVs, Roku, Fire TV, and Apple TV. Changing it there affects every app, not just YouTube.
This catches a lot of people out: they hunt through YouTube’s own menus on a TV and find nothing, because the control isn’t there.
Improving Readability Beyond Size
If captions are still hard to read on a bright video, size isn’t always the fix. Setting the caption background to black at full opacity often helps more than enlarging the text, since white captions over a light scene are the usual culprit. Switching to a heavier font weight helps too.
For Creators
You can’t set caption size for your viewers — it’s entirely a viewer-side preference. What you can control is caption quality: YouTube’s auto-generated captions frequently mangle names, technical terms, and accented speech, so editing them in Studio > Subtitles genuinely improves the experience for anyone relying on them.
FAQ
Is there a keyboard shortcut for caption size?
Yes — press + to increase and − to decrease caption size while captions are on, without opening any menu.
Why can’t I find the setting on my smart TV?
On a TV, caption size is usually controlled by the device’s system accessibility settings, not inside the YouTube app.
Do caption settings sync between my devices?
No. It’s a per-device viewer preference and doesn’t sync across browsers or devices.
Can creators set caption size for viewers?
No. Caption size is entirely a viewer-side setting — creators can only improve caption accuracy, not display size.