Mouse Hover marker to display new infoWindow (and close any previous open infoWindow). To show infowindow you should do following steps :
Step 1Go to Add or Manage Map and scroll down to ‘Infowindow Settings’ section.
Step 2Point to ‘Show Infowindow on’ option and select ‘Mouse Hover’ from drop down list.
Step 3Save the map and open it in a browser.

Video Tutorial