Windows 10 changes the default PDF viewer to Microsoft Edge. You'll need to change the default viewer to Adobe.
Changing the Default PDF Viewer in Windows 10
1. Click on Start Menu > Settings > System > Default Apps
2. Scroll down and select 'Choose default Apps by file type'
3. Scroll down and look for .pdf on the left side, click on 'Microsoft Edge' to select, once 'Choose an app' popup opens, select the application you want to set as default to open PDF file type, done.