...
https://support.google.com/chrome/answer/142056?hl=en
Chrome Browser
https://support.mozilla.org/en-US/kb/disable-built-pdf-viewer-and-use-another-viewer
FireFox users should also make sure all plugins are up to date for security reasons. Firefox provides a web page checkup for installed plugins:
https://www.mozilla.org/en-US/plugincheck/
Chrome Browser
https://support.mozilla.org/en-US/kb/disable-built-pdf-viewer-and-use-another-viewer