Adobe PDF Rich Text Feature

To enable the 'rich text' options, press Control + E keys on a Windows or  Command + E keys on a Mac. You can also enable the tool via the menu. Click the following on the menu bar: View > Toolbars > Properties Bar. For best results when using the "rich text" options, use Adobe Reader or Adobe Acrobat.  (Adobe Reader is free.)  Other PDF Apps/Software may or may not have the rich text function.

Editable PDF Fields & Rich Text Feature