Mouse Hover marker to display new infoWindow (and close any previous open infoWindow). To show infowindow you should do following steps :

Step 1: Go to Add or Manage Map and scroll down to ‘Infowindow Settings’ section.

Step 2: Point to ‘Show Infowindow on’ option and select ‘Mouse Hover’ from drop down list.

Step 3: Save the map and open it in a browser.