Right PDF (macOS) provides two editing modes: Write mode and Review mode. The features in Write mode are designed to make editing PDF documents easy and intuitive, while Review mode offers rich PDF functions such as annotation, signature, password and interactive forms. 

You automatically enter Review mode whenever you open a PDF document. But once you create a blank PDF, the default mode becomes Write mode. In Review mode, use the Convert to Writable feature to enable Write mode and transform your PDF into an editable document. Afterwards, you may switch between two modes at will until you click Prevent Further Edits.