If you want to extract highlighted text from PDF file as a plain text file, then this post covers some good free PDF Highlight Extractor software to do that.

When you're presented with a PDF form, the options for adjusting the size and style of the text are often limited. If you want to change the font in Adobe Reader, you might not find the solution ...

Removing text from a PDF isn't as easy as drawing a black bar across it. Fortunately, redaction tools let you truly erase sensitive text in Preview, Adobe Acrobat DC Pro, and PDFPen.