Help with forms

Can anyone help? I have designed a form and have protected it as usual. The problem is, that there is one field that the user needs to be able to format with tabs, inserting boxes etc etc etc, but as the form is locked it does not allow any changes to the formatting of that field.

My question is: Is there a way of Unlocking only one part of the form so that the user can have full menues to make any changes to the field. Would this be code driven? and is there any code that would help.

Any feedback would be appreciated. and a big THANKS to the the person who gave me the help with the drop down list question I raised.