ANDROID STUDIO How to go back to application from settings

I got some trouble with android studio I work in a company who has a web application so I worked on IOS application it was pretty easy but now I worked on Android and I'm not able to do a simple return to the application.

This the visual legacy :

When you open the application it answers you to allow some permission to the app :

[Popup to authorize permission] https://i.stack.imgur.com/Uz9Ox.png

Then you go to the settings : [Settings] https://i.stack.imgur.com/oqlfG.png

As you can see we implement additional settings to enter user ids ( mail, password ) :

[Additional settings ] https://i.stack.imgur.com/zn8Ll.png

You can see that there is a button below the inputs I want it to returns to the application but when I'm putting this code

Preference myPref = findPreference("backto");
myPref.setOnPreferenceClickListener(preference -> {
   startActivity(new Intent(getContext(), MainActivity.class));
   return true;
});

It doesn't send me to the application it creates a new instance of the application directly in the additional settings.

How can I make a function that send me to the app and not create a new instance ?

There is my additional settings class:

import android.content.Intent;
import android.os.Bundle;

import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
import androidx.preference.Preference;
import androidx.preference.PreferenceFragmentCompat;

/**
 * A simple {@link Fragment} subclass.
 */
public class SettingsFragment extends PreferenceFragmentCompat {

    MainActivity mainActivity;

    @Override
    public void onCreatePreferences(@Nullable Bundle savedInstanceState, @Nullable String rootKey) {
        setPreferencesFromResource(R.xml.preferences, rootKey);

        Preference myPref = findPreference("backto");
        myPref.setOnPreferenceClickListener(preference -> {
            startActivity(new Intent(getContext(), MainActivity.class));
            return true;
        });
    }

}