If you want the mouse pointer to move automatically to the default button in the dialog box in Windows 10, then follow these steps:
Go to the “Pointer Options” tab.
In the “Snap To” section, you’ll find the “Automatically move pointer to the default button in a dialog box” option. Select it.
Hit the “OK” button at the bottom.
Note: If you do not wish to use this feature, uncheck the above option and click on the “OK” button at the bottom.
Go to HKEY_CURRENT_USER > Control Panel > Mouse.
Double-click SnapToDefaultButton in the right pane.
Enter 0 (to disable) or 1 (to enable) in the Value data field.
Click the OK button.
Sign out and then sign back in.