I can't figure out what I am doing wrong. I am setting up a form for my
business to be able to enter addresses etc but when I go to the form field to
protect it the lock icon is grey and non-functional. What am I doing wrong I
know it has to be something simple.

you have set up all your fields, defined them, etc.? just click on the lock
icon on the FORMS toolbar. I have mine permanently docked at the bottom.