By default, Windows 10 opens PDFs in Microsoft Edge. Many PDFs that contain fillable forms work much better under Adobe Reader, and the instructions below will show you how to set Adobe Reader as the default program for PDFs.
1. Right-click on the thumbnail of the PDF file, and then click Properties.
2. In the file's Properties dialog box, click Change.
3. Choose Adobe Acrobat Reader DC and then click OK.
4. In the Properties dialog box, click OK.