When filling in a PDF form using Adobe Acrobat DC, determine whether the file is an interactive fillable document or a non-interactive flat document. For a fillable form, click on Highlight Existing Fields to highlight all fields and outline interactive fields a different color, making them easier to identify.

In a single-line text field, press the Enter or Return button to accept what you have typed in the box and deselect the field. Pressing Enter or Return with a multiple-line text field selected inserts a paragraph return. Press the Tab button to go to the next field on the form.

If the file creator did not covert the form to interactive fillable format, it is still possible to fill it out using the Fill & Sign tools. These tools allow you to insert text and symbols, such as check marks, anywhere in the document.