Script with replace some of the characters respectively

Question

I want to change some of the characters respectively
where error
app.findGrepPreferences = app.changeGrepPreferences = null; 
app.changeGrepPreferences.appliedFont = "Symbol";
app.findGrepPreferences.findWhat =  {"α", "é", "β"};
app.changeGrepPreferences.changeTo = {"à",  "é", "á"};
app.changeGrepPreferences.appliedCharacterStyle = myChar1;
app.activeDocument.changeGrep(); 
app.findGrepPreferences = app.changeGrepPreferences = null;

Answer 1

OK I writed a script
but How can I change the font of "a" character
main ();
function main(){
  app.scriptPreferences.userInteractionLevel = UserInteractionLevels.interactWithAll;
  if(app.documents.length >= 1){
                 var myDoc=app.activeDocument;
        editT(myDoc);
    else
  alert("Pleace Open İndesign Doc");
function editT(myDoc)
    var oldA =["a", "b", "c"]
    var newA =["1", "2", "3"]
    var changee =[["a",0],["b",0],["c",0]]
    for (var i=0; i<oldA.length; i++)
        app.findTextPreferences = NothingEnum.nothing;
        app.changeTextPreferences = NothingEnum.nothing;
        app.findChangeTextOptions.caseSensitive = true;
        app.findChangeTextOptions.includeFootnotes = false;
        app.findChangeTextOptions.includeHiddenLayers = false;
        app.findChangeTextOptions.includeLockedLayersForFind = false;
        app.findChangeTextOptions.includeLockedStoriesForFind = false;
        app.findChangeTextOptions.includeMasterPages = false;
        app.findChangeTextOptions.wholeWord = false;
        app.findTextPreferences.findWhat = oldA[i]
        app.changeTextPreferences.changeTo = newA[i];
        changee[i][1] = app.activeDocument.changeText().length;
        myDoc.changeText();
        app.findTextPreferences = NothingEnum.nothing;
        app.changeTextPreferences = NothingEnum.nothing;