Add new text anywhere on a PDF — labels, notes, fill-in responses or corrections. No install, runs in your browser.
Short answer: open the PDF in the editor, pick the Text tool, click on the page, and type. Style it in the right-hand panel and export.
For each field: place a text box, type your answer, and resize so it fits the line. Set the font size to match the form's existing type — usually 10 to 12 pt. For checkboxes, use the Checkbox tool.
PDF text can't be edited in place. To "replace" text, draw a white rectangle with the Shape tool over the old text, then add a new text box with your replacement on top. The original text remains underneath as invisible metadata — this is fine for most use cases but not for redaction where confidentiality matters.