Follow these instructions to edit the alt text for your image:
Click on the section with your image to edit it.
Note: If your image is associated with a collection item (Gallery Item, Product, Service, etc.), select the collection item first, then the image.
Under the Image or Media field, click the Info button.
Add your desired description to the Alternative Text field.
4. Continue to the next section to edit more image alt text or publish your changes!