Change Back Button Label



I’m having a problem creating my app.
I wont to change the label “Back” used by the back button on the navigation bar to other language, but i can’t find a way to do it.

I have try to put the button on the index.html, but it didn’t work. Here is the code.

<body ng-app="my-app">
        <ion-nav-back-button class="button-clear">
            <i class="ion-arrow-left-c"></i> Voltar

Then i try to implement my own button, on each view. It works, but the transitions between screens have become slower. Here is the code.

<ion-nav-bar class="bar-positive nav-title-slide-ios7">
  <ion-nav-back-button class="button-clear">
    <i class="ion-chevron-left"></i> Voltar

The same result for this aproach:

 <ion-view title="{{data.appname}}">
        <ion-nav-buttons side="left">
            <button ng-click="goBack()" class="button button-icon icon ion-ios7-arrow-back"> Voltar</button>

Is there any way to change the button label, and keep the performance?
Update: It was missing the back button present on the left menu. This one is fix.