Shopify buttons and checkout in different languages

[PanRuft]

Hello, i am operating a website in two languages and wish to add shopify buttons. While I am able to create different buttons for one product to insert it in the proper language i need to have the a checkout page in two different languages at least, German and English. It could depend on the default setting of the browser of the customer or at least be switchable or depend on where the selling process was started from, a German page or English one. I am using WordPress and the language tool WPML. So the different languages are located on different pages. Any idea how this could be done? Also i tried to switch the language of the checkout page into English, but it is greyed out, and only in German available. Any one any idea? thank you! Pan