Language and Currency unable to change

I have installed OC 3.0.3.8 running on php 7.4. I have also installed Turkish language pack and set it as default language. On admin side, all is fine. However, client side can not change language or currency. Selector is there, shows the two languages, just doesn't change anything. Same with currency.
My chrome browser's default language is English and the store shows me English version and USD currency. Neither language or currency can be changed.
With my andorid browser, store shows me Turkish version and TL currency. Neither language or currency can be changed.
Help will be appreciated.

Check both your OpenCart and PHP error log. Also check your web browser's developer console.

More details please, such as website URL, theme, extensions, etc., as per the forum rules.

Right. website is https://www.agrolit.com.tr
No theme was installed except for first install theme.
After reporting this issue I've come to discover that it works fine on another PC running Chrome and a Mac running Safari. The site exhibits this behavior only on my Windows 10 Home running Chrome Version 122.0.6261.131 (Official Build) (64-bit). I'm just concerned that in time, some customers might experience this.

works fine from here.
maybe ope webtools in your browser and see if the cookies hold.

Works fine here, too, using FireFox 124.0.2 (64-bit).