this is a help site designed for coders that hit a wall, not really a substitute for using quick google search and the many free pages and tutorials on managing and tweaking such a popular third party platform.
For example, searching google for "woocommerce custom add to cart button" showed how to affect the urls and text, and a search for "woocommerce add custom button" showed how to add extra ui buttons in various pages.
And as others posted here, there also appears to be many plugins making that even simpler, a few of which show up in those searches i listed above, such as "min/max quantity"
https://wordpress.org/plugins/woo-min-max-quantity-limit/
https://wordpress.org/plugins/minmax-quantity-for-woocommerce/
Please see https://stackoverflow.com/help/how-to-ask if you try implementing those, hit a wall and cant find anything (after searching for a while) to work around it.
Hope that helps too