If you have the voice remotes you need to remember to point them at the tv to work. They are Bluetooth to the Fios box, but infrared to the tv. If you still can't get them to work go to: settings>voice control>fios voice remote>Program Fios voice remote>Manual setup and follow directions to setup your make and model of tv. Don't forget to restart Fios Box afterwards.
Try this from support:
1. When the setup has a Receiver/Audio device b/w STB and TV and connected via HDMI, Make sure it is powered ON. Sometimes the Receiver/Audio device can be powered OFF and because of that, the remote might only be auto programmed to TV and not to the Receiver/Audio device
2. If you don't see Volume change during programming process (either Auto or Manual), Select the option: No - Let's try another code set for your TV.
Try this a few times until you see volume change or else enter the Model# manually
3. Make sure remote is pointed directly to the device (TV or Receiver/Audio device) when pressing "OK" to test Volume or Power.
Please note that only the OK key is used for both Volume and Power tests during the programming and using any other key during the setup might hamper the programming flows.