I see, you're testing an existing users invoices by viewing an invoice that has already been stored. Changes to the invoice text won't take affect for already stored invoices as the full name is stored in the database and not substituted or calculated again.
Please test by attempting to make a new purchase and you'll see the titles take affect after making a successful subscription. I've added LONG- and SHORT- for the payment texts so you may see where the usage is applied.
We do not advise changing a plan once users have subscribed!