Hi,
You can't enable it for a currency. You have to check that the plugin accept the currency you are using.
If the plugin itself does not support the currency, it means that the payment platform won't accept it. So it won't be a good idea to force the support of a currency which is not accepted by the payment platform.
When you are creating a new payment configuration, you see the list of the payment plugins and the currencies you are currently using.
Thanks to this table, you can know if the payment plugin support your currencies, and which one.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.