How to translate shipping method titles

I need to change the text for a shipping method title.

Currently we have

Federal Express

Express Saver

I would like this to say Express Saver (3 Day Delivery) instead of Express Saver on the shopping cart/check out pages.

I have added this line to my custom themes translation file however it doesn’t work. Where can I edit this text? I obviously don’t want to modify the core fedex module files.

/home/website/public_html/app/design/frontend/Smartwave/porto_child/i18n/en_US.csv  "Express Saver","Express Saver (3 Day Delivery)",module,Magento_Fedex 

I also tried putting the string here with no success,

/home/website/public_html/app/i18n/en_US.csv  "Express Saver","Express Saver (3 Day Delivery)",module,Magento_Fedex 

Thanks