alt tags

I want to change the Alt language on some of the image links. How do I do that? Where are these Alt tags defined? I've looked through dozens of pages of code and been searching the forum here and the web in general for hours looking for the answer.:frusty:
Its probably right in front of me but if it is, I can't see it. Anyone know?

If you're referring to alt text on "additional" product images, there is presently no facility built-in to set different text for each image. Instead, for products, the alt text is taken from the product name.

Or are you referring to some other set of images?

Should have been clearer. I'm referring to the alt tags for the buttons. for instance the "category home" button on the product info page (between 'next' and 'prev') currently has a Alt tag "return to the product list". i want to modify that a bit as well as some of the other button alt tags.
Hope that's clear.
Thanks

For buttons, there is a "button_names.php" language file in which you can customize the alt text (2nd half of the file).
Additionally, you can typically locate such a location by using the Developers Toolkit and searching for the text you want to change ... ie: "return to product list"
https://www.zen-cart.com/tutorials/index.php?article=38
https://www.zen-cart.com/tutorials/index.php?article=39

Remember to save you language-file edits to an override folder.