Q: Cannot change Login Window Text before Filevault

I have set the Login Window Text to include my phone number and other things, but this information is outdated. So I have changed the text and it shows correctly when my computer is locked, but when I reboot or startup from hibernation the old message still appears when it asks for my Filevault password.

How can I fix this?

I am running OS X Sierra (which was updated from El Capitan) with Filevault enabled.