Opening file with wrong encoding

Hi, i have some gsp file with ISO8859-1 encoding, with the charset tag

<%@ page contentType="text/html;charset=ISO-8859-1" pageEncoding="ISO-8859-1" %>

and intellij have the right charset in the corner 

When i write the characters are in the right encoding, also when i close the file tab and open again from the project structure view (alt+1) but when i close Intellij and open again the file are opened with UTF-8 showing the � character everwhere, but the file still in ISO-8859-1 (checked with the notepad++) until i write something in the editor and the unknown ISO characters overwrite with � utf-8 character.