custom field checkbox does not save

-- url of the page with the problem -- : ententiki.sk/index.php/hikashop-menu-for...ies-listing/checkout
-- HikaShop version -- : 4.0.2
-- Joomla version -- : 3.9.3
-- PHP version -- : 7.2.7
-- Browser(s) name and version -- : chrome

When customer makes registration on checkout page there is checkbox with advert email confirmation.
Default value is set to checked
When I try to register and I uncheck this checkbox, it does not save this unchecked value. In customer list this value is set to checked.
Can you please help me with this problem.
thank you

Hello,

Several thing to say about your case.
About using Custom field Address, we don't follow you because a Address type custom field isn't displayed in Backend customer list... From here, there must be something more to check on your side, you have create several custom field and maybe there is confusion somewhere.

Plus, if you use an address custom field, means that each time a customer create a new address, it will have to check or uncheck your
custom field, this isn't really logical...
=> You want to use a User type custom field, means that this question will be ask only once, while registration process
OR
You can use with Acymailing that is able to add this kind of checkbox in order to automatically register user in news letter process.
Maybe you can have a look on this to have more elements about what Acymailing can solve for your issue.
Hope this will help you to get what your needs.

Regards