This guide is for your Paypal account . In case you want to convert US$ in Euro or Euro to US$ or any currency to another 
First you must login to your Paypal account .
After you are logged you will see the button Manage Currency .
Click it and you will go to this page :
Select the currency you want to convert in ( example : from US Dollars to Euro )
After you select and press Convert
You will be on this page :
Select the ammount , the currency to convert in and press Continue .
You will be on this page :
Now you can press Convert and you are done!
That’s All , hope you like it 