Airport utility does not recognize Airport Express -have changed to a Verizon FIOS Modem/router
Unless you have reset the AirPort Expresses back to factory default settings, they are still programmed with the settings to connect to your "old" network.
At the present time, the AirPorts have no idea how to connect to your Verizon network, so AirPort Utility will not "see" them because they are not connected to the same network that your Mac is connected to.
Reset one AirPort back to factory default settings and then run AirPort Utility to set up the AirPort to connect to the Version network wirelessly. (An Ethernet cable is not required for this).
Then, set up the second AirPort the same way.