Creating digital forms?

I have some forms I created with Acrobat that I'd like to convert to digital.

Do I password protect the entire document but leave optional fields unprotected? How would I do that?

For example, I'd want the title and copyright information and so on protected so the user couldn't alter it, but leave some fields like date or quantity "open" so the user could enter whatever they want and reuse the form as many times as they want.

Thanks in advance!