"Thank you for contacting PayPal Merchant Technical Support.
Let me begin by apologising for any confusion caused. I accept that issues like yours can be very confusing and I hope that by clarifying the situation and offering you the right advice I can help you resolve it.
Firstly, to clarify, you are using Express Checkout with Zen cart is that correct?
(me - yes)
If so, rather than using "lc" you will be using the variable "LOCALECODE"
As per Chapter 3 page 28 of our developer's guide:
directly into the SetExpressCheckout request being passed to PayPal, the language of the PayPal checkout will change.
Having said that, I appreciate that by using Zen Cart to implement your checkout, you may not have direct access to the code in order to make the required changes. I would therefore encourage you to contact Zen Cart support directly and request that they add this information into the SetExpressCheckout request that is generated by your cart for you. PayPal does not have access to the code generated by Zen cart to make this change.
Without passing this information, the PayPal login/ billing information page will be set to that of the merchant's PayPal account. This means that the Rosetta country menu (the drop-down menu at the top of the PayPal checkout) will only be displayed if it detects that your customer's browser does not contain an Italian cookie. By this I mean, this menu will only be displayed if the person testing has never visited an Italian site previously.
To conclude, if your Zen Cart administration panel for:
modules -> payments -> Express Checkout
does not provide you with the option to select language/ display country,
(me - it doesn't!)
you will need to contact Zen Cart directly and request that they pass "LOCALECODE" for you."