Alt text did not change, or I want it reverted

Alt text is generated and written separately from resizing, so a resize run leaves it untouched by design. Two limits are worth knowing: Shopify caps alt text at 512 characters, so long generated text is trimmed to fit rather than rejected; and alt text has its own revert operation, distinct from restoring the image itself, so undoing one does not undo the other.

Check these in order

1. Did you run Alt Text?

   Resizing never writes alt text. Open Alt Text and run it on its own.

2. Was the image already described?

   With Only fill in images that have no alt text ticked, which is the default, images you already described are left alone.

3. Is the text longer than 512 characters?

   Then it was trimmed to fit.

How to fix it

To replace existing wording, untick Only fill in images that have no alt text and run it again. To revert, open the alt text run in History and press Undo alt text; where an image had no alt text before, it goes back to blank.

If it still is not working

Send us the alt text run you are asking about: contact support.