diff --git a/android_app/app/src/main/java/com/health/openscale/gui/MainActivity.java b/android_app/app/src/main/java/com/health/openscale/gui/MainActivity.java
index 62de40e7..1a583c69 100644
--- a/android_app/app/src/main/java/com/health/openscale/gui/MainActivity.java
+++ b/android_app/app/src/main/java/com/health/openscale/gui/MainActivity.java
@@ -101,8 +101,7 @@ public class MainActivity extends AppCompatActivity
 
         super.onCreate(savedInstanceState);
 
-        PreferenceManager.getDefaultSharedPreferences(this)
-                .registerOnSharedPreferenceChangeListener(this);
+        prefs.registerOnSharedPreferenceChangeListener(this);
 
         CaocConfig.Builder.create()
                 .trackActivities(true)
@@ -203,8 +202,7 @@ public class MainActivity extends AppCompatActivity
 
     @Override
     public void onDestroy() {
-        PreferenceManager.getDefaultSharedPreferences(this)
-                .unregisterOnSharedPreferenceChangeListener(this);
+        prefs.unregisterOnSharedPreferenceChangeListener(this);
         super.onDestroy();
     }
 
@@ -317,7 +315,6 @@ public class MainActivity extends AppCompatActivity
                 return;
         }
 
-        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(this);
         prefs.edit().putInt("lastFragmentId", menuItemId).commit();
 
         FragmentManager fragmentManager = getSupportFragmentManager();
@@ -416,8 +413,6 @@ public class MainActivity extends AppCompatActivity
 
         bluetoothStatus = menu.findItem(R.id.action_bluetooth_status);
 
-        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(this);
-
         // Just search for a bluetooth device just once at the start of the app and if start preference enabled
         if (firstAppStart && prefs.getBoolean("btEnable", false)) {
             invokeSearchBluetoothDevice();
@@ -448,8 +443,6 @@ public class MainActivity extends AppCompatActivity
             return;
         }
 
-        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(this);
-
         String deviceName = prefs.getString("btDeviceName", "-");
 
         boolean permGrantedCoarseLocation = false;
@@ -597,8 +590,6 @@ public class MainActivity extends AppCompatActivity
         OpenScale openScale = OpenScale.getInstance(getApplicationContext());
         final ScaleUser selectedScaleUser = openScale.getSelectedScaleUser();
 
-        final SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
-
         Uri uri;
         try {
             String exportUri = prefs.getString(getExportPreferenceKey(selectedScaleUser), "");
@@ -686,7 +677,6 @@ public class MainActivity extends AppCompatActivity
                 break;
             case EXPORT_DATA_REQUEST:
                 if (doExportData(data.getData())) {
-                    SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(this);
                     SharedPreferences.Editor editor = prefs.edit();
 
                     String key = getExportPreferenceKey(openScale.getSelectedScaleUser());