Auto translate into browser language no work 2nd time

Hi developers,

I have a question regarding to the function of translating to browser language. I built my website in English. I check with browser with incognito mode in German . For the 1st time is German. Then i close the browser, and open my website with incognito mode again, it is back to English again. Even in this time, i change the language into German, but when i close and reopen, it’s back to English. I would like to ask if developers have solutions for this.

I build an ecommerce store, and the client may access to the website several times before deciding to buy the product. I mean not only in my case, but also in general that this improper function of gtranslate will significantly reduce the web user experience since the 2nd, 3rd time visit is clearly different to the 1st time.

Thank you.