If you asked to change the email address on your account, a message arrived, you followed the link in it — and nothing happened. The address stayed as it was. The link stopped working afterwards, which made it look as though it had done its job.
Two things were wrong at once, and together they hid each other.
The account required the change to be confirmed from both the old address and the new one. Following one link alone left the change half-made, waiting for a second confirmation nobody had asked for. And the page you landed on said nothing at all: a completed change and an expired link both dropped you back at the same screen in silence, so there was no way to tell which one you had.
A change of address is the one thing you cannot verify anywhere else in that moment. If the system does not say what happened, nobody can.
What is different now. One message goes to the new address, and one click completes the change. The page then names the address your account has moved to, so you are not left guessing. If the change cannot be completed — an expired link, most often — the page says so plainly, states that your address is unchanged, and takes you back to your settings.
Your previous address is now notified. When the change goes through, a short message goes to the address the account has just left, saying which address it moved to. If somebody else ever changes the address on your account, you find out at the address you still control.
While a change is awaiting confirmation, your settings screen now says so, rather than looking as though nothing was requested.