Currency reporting in Google Analytics is customizable at the View level - and by default, every new view uses US Dollar as its currency. It's really easy to change it:
Log into your Google Analytics account
Navigating to your property (your store or website) view
Hit View Settings,
Change the setting titled Currency displayed as
Remember to hit Save and you are good to go.
To change the currency you use for Facebook ads:
Go to your ad account settings in Ads Manager
Under Currency, click Change Currency
Select your new currency and time zone, then click Create New Account
By choosing a new currency and time zone, you've created a new ad account.
Your old ad account is still visible in the Account drop-down in the top left of your Ads Manager, but it's closed and all ads created with your old account stop running. Any ads you had running on the old ad account are billed in the old currency.
Note: If you're using monthly invoicing to pay for your ads, it's not possible to change your currency once your ad account has been created.
Note: You cannot change the currency in Google Ads after creating an account.
Therefore, if Google Ads is being used, it is important that you change currencies within your other ad accounts to reflect the currency being used in Google Ads.