I cannot change text in woo subscription button

I followed this instructions given by woo subscription developer to change the text in a button. I have a screen shot that this works on his side, but it doesn’t on mine. Any suggestion as to what to do?

1. Head over to your Dashboard and navigate to Tools > Text Changes. 
2. Click on the ‘Add New‘ button at the top of the page. 
3. Please add a new text change function with these exact parameters:
   1. Original string: Switch subscription
   2. Text domain: woocommerce-subscriptions
   3. Text content: add to cart button text while switching a subscription
   4. Replacement string: Upgrade (or whatever you’d like it to say)

Any help is sincerely appreciated.

The page I need help with: [log in to see the link]