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.
mouse-hover-event
Step 3Save the map and open it in a browser.

Video Tutorial