Check if the document is a scanned PDF document. Check if it is a secured/encrypted PDF document. Use the Rectangle tool to highlight text. Repair or uninstall Adobe Acrobat Reader.

PDF files enable you to share and comment on content created in a wide range of applications. Adobe Reader, formerly called Acrobat Reader, offers a subset of the capabilities of the paid Adobe ...

2. Open the PDF document in Adobe Reader. If it isn't already the default PDF viewer on your computer, right-click it, hover your mouse over "Open with," and select "Adobe Reader" in the list. 3.