DefaultTrackSelector in ExoPlayer not working ! (other way?)

Question

I am developing a live stream and movie player application. I chose ExoPlayer 2. The movie has two different tracks include (English and Persian). In others i found these solutiones but not working for me. I want sth like a button in playing movie that when i click, it switches between tracks. can you help me?

trackSelector.setParameters(
trackSelector
    .buildUponParameters()
    .setMaxVideoSizeSd()
    .setPreferredAudioLanguage("fa"));

and also

trackSelector = new DefaultTrackSelector();
trackSelector.setParameters(
        trackSelector.getParameters().buildUpon().setMaxVideoSizeSd()
        .setPreferredTextLanguage("fa")
        .setPreferredAudioLanguage("fa").build());