How to use EUR in Paypal Sandbox
The default currency is decided by the country you choose when you create the account. To automatically accepet transactions that are not in your default currency you can choose "Allow payments sent to me in a currency I do not hold:" from here
Create a new paypal sandbox account from here
Select country from here..
Note: The default currency is decided by the country you choose when you create the account. And the default paypal sandbox Accounts consist the default/local currency..Best option is to create new sandbox account.