Hello @Recep,
We have reviewed the issue related to adding items to the cart but were unable to reproduce the same problem on our side: https://gyazo.com/c846dd735316f38bfc44e79c92c05480.
Additionally, to check the “My Account” page, we will need access to your website, as this page is visible only to logged-in customers.
Best regards,
Jack Richardson
8Theme Team