As of 20 September 2026. The video plays in a floating window, but subtitles stay on the webpage? This desktop Firefox guide helps distinguish a fixed browser issue from a missing or unsupported subtitle track. It is useful, for example, when watching lessons alongside your notes.
Why this matters now
Firefox 156.0 was released on 15 September 2026. Mozilla lists a fix for subtitles not appearing in Picture-in-Picture when enabled in the video player after the floating window had already opened. This concerns a specific activation order, not a promise covering every video or streaming service. The evidence concerns the desktop Release channel; this guide does not establish the same fix for ESR, Android or iOS. [1]
Before you begin
You need a working Firefox installation, a video you can legitimately access with a selectable subtitle track, and a few minutes for comparison. Note the version, operating system, subtitle language and original sequence. Save open work before restarting. On managed devices, IT remains responsible for approved updates. Do not buy a subscription or extension for this test.
Six safe checks
- Check the regular player first: close only the Picture-in-Picture window and enable the desired track on the video page. Play a passage containing speech. If text is missing there too, investigate the track, language or website before the floating window.
- Enable subtitles first: keep the working track enabled in the page player, then open Picture-in-Picture using the available video toggle. Mozilla describes this as the normal sequence for supported websites. It also provides a low-impact comparison with the reported issue. [2]
- Compare the same video: check the same passage and language in the floating window. Record whether text now appears. A difference suggests a connection with the order of actions, but alone proves neither the precise cause nor a problem with every video.
- Use the intended update route: for a Mozilla installation, open Help → About Firefox; on macOS, About Firefox is in the Firefox menu. Checking can download an update. Store installations and Linux packages are updated through their respective provider. After the required restart, check the version again; do not downgrade or force a channel change. [3]
- Repeat the original sequence: after updating, open Picture-in-Picture and then enable subtitles in the page player. Compare the same passage again. For a managed ESR installation, consult its release notes or IT rather than assuming the 156.0 fix applies.
- Narrow the scope: if possible, compare a second freely accessible video with a working subtitle track. Record whether only one website fails. Mozilla supports selected services and WebVTT-based subtitles; that does not automatically cover every proprietary player. [2]
If the problem remains
If supported sites still fail, Firefox Troubleshoot Mode can provide another comparison: Help → Troubleshoot Mode, then Open, not Refresh Firefox. It temporarily disables extensions and hardware acceleration, among other features. Use only a non-sensitive test video and follow IT policy. Success does not identify any one extension as the cause. [4]
Verify the result and go back
Success means the same selected track is readable in Picture-in-Picture at the relevant passage, including with the previously failing activation order. Check again after a normal restart. To go back, close the floating window and use the page player; exit Troubleshoot Mode by quitting and starting Firefox normally. Do not delete the profile or cookies, permanently disable protections or install unknown codec packs. Support needs the version, website and steps, not account details or private video links.
Sources and transparency
Source-based editorial troubleshooting, not our own Firefox reproduction test or benchmark. No affiliate links or purchase recommendation. The occasion is a dated manufacturer fix, not a claimed search trend.