When asked if you want to change all similar documents, click Continue.Choose either Adobe Acrobat or Adobe Reader from the application menu.Click the arrow next to Open With to expose the product menu.In the Finder, select a PDF, and choose File > Get Info.To switch from the built-in PDF viewer to Adobe PDF viewer Safari: Where it says 'Download PDF files instead of automatically opening them in Chrome' click on the toggle button to enable Chrome to download the PDF instead of opening in Chrome.Open Chrome and type “chrome://settings/content/pdfDocuments” in the URL bar in the browser.

To switch from the built-in PDF viewer to Adobe PDF viewer Chrome:

Click on the drop-down arrow in the Action column for the above entry and select Use Adobe Acrobat (in Firefox).

Find Portable Document Format (PDF) in the Content Type list and click on it to select it.

At the top of the Firefox window, click on the Firefox button and then select Options (if you have an older version of Firefox, Options may be found by clicking the Tools button at the top of the window).

To switch from the built-in PDF viewer to Adobe PDF viewer Firefox: Please follow the instructions on how to change Chrome, Firefox or Safari to open PDF files using Adobe Acrobat Reader instead of the browser built in PDF reader. There is a UserVoice suggestion addressing this issue, with a lot of votes, but so far there is no communicated road-map from Microsoft for this feature. Instead they are opened in SharePoint’s file viewer. If you have experienced any problems with opening 'Fillable' forms on the Attorney General's Office website while using Chrome, Firefox or Safari. Currently Office 365/SharePoint online does not support opening PDF-documents directly in the client application (Adobe Acrobat Pro/DC). How to disable the built-in PDF viewer and use Adobe Acrobat Reader Illinois Attorney General - How to disable the built-in PDF viewer and use Adobe PDF viewer Skip Navigation

Open pdf in acrobat from chrome