Windows 10 requires you to click the window to activate it by default.
To make the window active by hovering instead of clicking, follow the steps below:
If you’re using the “Category” view, click on Ease of Access. Otherwise, click on Ease of Access Center.
Hit the “Change how your mouse works” or “Make the mouse easier to use” link depending on what you see.
Select the “Activate a window by hovering over it with the mouse” option. It can be found in the “Make it easier to manage windows” section which is beneath the Control the mouse with the keyboard section.
Hit the “OK” button.
Note: For the default setting, unselect the option above and click the “OK” button.