You may edit this value. You can also set a radio button field to be checked by default. PDF radio buttons function differently than HTML form radio buttons. Top do this first add two or more radio buttons to your form. You may wish to make one of the fields selected by default.
Text fields have many purposes.
Most often they're used for user entry of free-form text. The other form field types are used to control user input. Text fields can limit the number of characters a user enters. Simply set the maximum number in the text options tabs when adding the field. Text fields can also be used for password entry.