[Plugin: NextGEN Gallery] adding language code for paypal simple plugin

I am using paypal plugin with NextGEN Gallery, now I am trying tp change the the language of the checkout page on paypal to Hebrew..on paypal support the told me I have to add this code “lc=he_IL” , but I have no idea where I have to add it, I am not very good with programing..
can I have some help?

Thanks!

https://www.ads-software.com/extend/plugins/nextgen-gallery/