Hello,
Could you please provide more details? Provide the page URL and screen of which button and how you want to change that.
You can translate/rewrite all theme and plugin texts via PO file in WordPress. Here is a video tutorial that should help you translate your website texts with a Loco Translate plugin https://www.youtube.com/watch?v=D3NsDdMzsls&list=PLMw6W4rAaOgKKv0oexGHzpWBg1imvrval&index=3
Please check the video tutorial to see how to save the translation file correctly. You can remove the plugin and translations would remain. Also, translations would remain after each theme update.
In order to translate the WooCommerce strings, you need to create a separate translation in Loco > Plugins > WooCommerce in the same way as shown in the video.
Best Regards