When our PhpEd Team4 license was renewed, four new serial numbers appeared on our "My Products" page.

How do we update the installations to reflect the new serial numbers?

I ask because upon installation of the latest PhpEd (from 21032 to 21033) there was no prompt to put in the new serial number. Is this because the renewal happened during the same Major version of PhpEd? Is this something we need to worry about at all?

Builds 21033 and 21032 are maintenance updates, so the major and minor versions remain unchanged. The serial number you already have for version 21.0 will continue to work.
When you install a new major or minor version, however, you’ll be prompted to enter the serial number again for the first time.
Note: You need to track which developers are using which serial numbers.