Inventory the audio actually present
Before configuring a language preference, open one file with known alternate audio and inspect the tracks it supplies. The language of the device interface is not evidence that the file contains that spoken language. Keep the intended track and its actual content distinct from a label copied into the filename.
Choose a short dialogue passage so the result can be checked by listening, not just by reading the menu label. Keep subtitles unchanged during the first comparison. A translated subtitle can make the programme understandable while the audio remains in another language, so note those two selections separately.
Inspect the documented default-track choices
Long-press the gear; compare language, device-language and file-default audio preferences. Record the starting choice. For an original sample, use a file whose main track and commentary share a language, then listen to a known scene. This reveals why a preferred-language match alone may not identify the programme audio a viewer actually wants.
Decide which behavior you want when several tracks are present. A device-language preference and a file-default preference answer different questions. If two tracks share a language, inspect their labels and content for commentary or another role. Language alone may not distinguish the main programme audio.
Reopen the same item and listen to the result
Apply one intended preference and reopen the representative file through the same source route. Inspect the selected track and listen to the known passage. A preference that appears saved is not the same observation as the intended track actually being selected on the next opening.
If the track differs from expectation, compare its metadata and the app’s current selection before changing the Android system language. Keep the file, device and app version fixed for the test. A file with missing or incorrect language metadata can create a different result from another file with accurately labelled tracks.
Check a missing-language case deliberately
After proving the preferred-language case, try a second authorized sample that lacks that language, if you need to understand fallback behavior. Record what the actual installation selects rather than inventing a universal fallback rule. Keep a manual track-selection route available for unusual files.
The expected outcome is a preference with observed behavior on a representative file and a known fallback case. It does not add a language to the source, dub a programme or establish that every service offers the same audio choices. Preserve the final setting in your device notes so another viewer can understand why a track was selected.
Questions answered
Can setting a language make missing audio appear?
No. The preference chooses among available tracks. The source must actually contain or supply the requested audio.
Why should I listen after checking the selected label?
A label can be incomplete or incorrect, and several tracks can share a language. A known dialogue passage confirms the actual selected content.
Sources & further reading
Official references for the subjects discussed. Service terms and device software can change.