In this lecture I show you how to enabled multiple currencies in your free Salesforce account (do not enable multiple-currencies in your workplace organization if you do not have the proper authorization). I also address how to log a case for a free developer account, helpful support phone numbers for Salesforce support, and how to enter initial exchange rates as well as add additional currencies to your org.
Email From Salesforce Support to Confirm Enabling Multiple Currencies - https://help.salesforce.com/articleView?id=admin_enable_multicurren&type=5
Enable Multiple Currencies Help Article - https://help.salesforce.com/articleView?id=admin_enable_multicurrency.htm&type=0
I then demonstrate what the impact is on Opportunities once you have enabled multiple currencies.