By default Windows 10 attempts to open Adobe .pdf files with its Edge browser instead of Adobe Acrobat.
In order to disable Microsoft Edge's PDF feature, you need to change the file association, which you can do with the following steps. There are two processes listed below. Choose which is easier for you.
Using the Settings app
1. Press and hold the <Windows logo key> and press the X key –or- right-click the Start button to bring up the Quick Menu, then left click Settings.
2. Click on Apps.
3. Click on Default apps.
4. Click the Choose default apps by file type link.
5. Scroll down and find .pdf (PDF File), and click the button on the right side, which is likely to read "Microsoft Edge."
6. Select your app from the list to set it as the new default.
7. Click the Switch anyway link to confirm the change.
Once you completed the steps, Microsoft Edge will no longer open PDF files by default in the web browser.
Using the file context menu
Alternatively, you can quickly make another app as your default PDF reader, using the following steps:
1. Right-click a PDF file.
2. Select Open With.
3. Click on Choose another app.
4. Select the PDF application you want to use. Adobe Acrobat in our instance.
5. Check the Always use this app to open .pdf files option.
6. Click OK.
If you don't see the app you want to use in the list, click the More apps link at the bottom of the list. You can also click the Look for another app on this PC to find the PDF application you want to set as default.