Apple ID First and Last Name Won't Update (Apple ID greyed out in iPad settings)

You have a configuration profile installed that Disables Account Changes. In Restrictions of the profile it'll have 'Allow modifying account settings' unchecked. It'll need to be removed (unscoped) from your iPads before you can access the Apple ID screen to log out and back in. Or you could check the option and redeploy the profile and then reverse the change later.

[edit] @Aquanex2

I would also like to note that having ONE Apple ID for all your devices, is NOT a smart thing to do. How many devices? More than 5? This will cause you a lot of pain. Do you have Apple School Manager or Apple Business Manager? (not familiar with ABM, understand its not quite the same as ASM), so you can create managed Apple Id's? You can create, or should create one for each device/user. You also get 200 gigs of free space with each Managed Apple ID's, as well, as you don't have to worry about saving pictures when you wipe a device. One Apple ID for all your device's is a lazy man's way of doing things, but problem is, your creating yourself a headache. Creating regular Apple ID's is a pain, but managed Apple ID's are very easy for admins to create. Ask your Apple rep about that.

@cdenesha Thanks this was it. Sorry for late reply.

@cpominville

Do you have Apple School Manager or Apple Business Manager

Yes we do have ABM. I should have mentioned that. All of our devices are managed under one ID, so it isn't that difficult to change First and Last names or other settings.

aquanex2 all under one Apple ID, will create new problems for you... ie, when they take pictures, all the pictures of all the users will be in one big pile. Having individual apple ids, in the long run..is best.