How to change App Description in Test Flight invitation e-mail?

I have an iOS app build ready to test. Some testers have been already testing. However, I need to change this part of Test Flight invitation e-mail for other testers who haven't been invited yet:

How can I do it? I have already tried:

• Editing TestFlight -> Test Information -> Beta App Description
• Editing TestFlight -> Builds -> my build -> Test Details -> What to Test

with no results. The text in e-mail always remains the same.