By default, Windows notifications disappear five seconds after they appear. If you want more time to read them, increase the notifications display time as follows.

Select the  button, then select 

Under Show notifications for, choose the time you want up to five minutes.

You don't get notifications at all? You might need to change the Focus support in Windows. Read the linked article for how to make these changes: https://support.microsoft.com/en-us/windows/make-it-easier-to-focus-on-tasks-0d259fd9-e9d0-702c-c027-007f0e78eaf2