The Built-in PDF Viewer
Google Chrome comes equipped with a highly capable, native PDF viewer, allowing you to read documents without needing external software like Adobe Acrobat. By default, when you click and drag your mouse across text within a PDF in Chrome to select a paragraph, the browser automatically highlights that specific text block in a bright blue color. While this is the standard visual indicator that text has been successfully selected and copied to the clipboard, it can be distracting if you simply use your mouse cursor to track the lines you are reading, as your document becomes covered in temporary blue boxes.
Altering PDF Selection Behavior
Unfortunately, Google Chrome does not offer a toggle switch to disable the visual text selection highlight within its native PDF viewer. To stop Google Chrome from automatically highlighting PDF text when you drag your mouse, you must change how Chrome handles the files entirely.
The only way to avoid the blue highlight is to force Chrome to download the PDFs and open them in a dedicated third-party reader (like Sumatra PDF or Apple Preview) where you can customize the highlight colors or disable them entirely. Open Google Chrome. Click the three vertical dots in the top-right corner and select Settings. In the left-hand navigation pane, click on Privacy and security, then click Site Settings in the main window. Scroll down to the very bottom and expand the Additional content settings menu. Click on PDF documents. You will see a toggle labeled Download PDFs (or “Download PDF files instead of automatically opening them in Chrome”). Turn this toggle On. Chrome will no longer render the PDF itself, thereby eliminating its hardcoded highlighting behavior.