How to get a price for every size instead of price range?

There are two price positions on a product page. The top position is showing the range correctly – this does not alter when a variation is selected.

There is a lower position that shows the price of the selected variation. It only appears when one is selected. This is not showing on your page due to some defect in the page template. You will need PHP skills or a developer to fix that. Load up Storefront to see how it should behave,

Ive got some PHP skills I have developed my theme on my own. Could you maybe point me to the direction how to fix this?

or maybe could you tell me how to find out which error does that?

There is a guide here:
https://docs.woocommerce.com/document/third-party-custom-theme-compatibility/

You could try to see how Storefront works.

You could be in for some late nights. I’d check out some WooCommerce-compatible themes first.

thanks this helped!