Once you create a metafield and set the name, the customer accounts hub app captures those names and is able to add them to the 'customize > language' section of the app.

This means that if you'd like to update the text your customer will see, you'll need to update the name in the 'customize > language' section.

You'll find all of your metafields under 'Custom Data Labels (Customer & Order Data)' inside of the 'customize > language' section: