Windows by default might not open your document in the preferred App. The most common change is your mail app to Outlook, browser to Chrome, and PDF to Acrobat. 

Changing default applications

Step 1: Default Apps in Settings

• Search for the word "default" in the search bar in the bottom left
• Click on the "Defailt apps" system setting at the top of the list

Step 2: Change Mail app

• Click on the "Mail" app under the email heading
• Select "Outlook"

Step 3: Change Browser

• Click on "Microsoft Edge" under the web browser heading
• Select Google Chrome
• Select "Switch anyway" on the popup "Before you switch"

Step 3: Change PDF

• At the bottom of the settings page there is an option "Choose default apps by file type". Click on it

• The list on the left is in alphabetical order. Scroll down until you get to the .pdf entry
  
• Click on "Microsoft Edge" under the pdf entry. 
• Select "Adobe Acrobat" or "Acrobat Reader"