How to change and save switch preference summary

So I recently joined the Kotlin train, and I have a fragment which changes the theme of my android app, I made the fragment restart after successfully switching theme, and then from the MainActivity reopen the fragment using a bundle set earlier in the fragment.

All these work. The problem i'm having is I also tried to change the android:summary field after switching theme, but each time the activity restarts, it switches back to the default summary value

What could I be doing wrong?

SettingsFragment.kt

       findPreference(getString(R.string.key_dark_theme)).setOnPreferenceChangeListener { preference, newValue ->
                    preference.isEnabled = false
                    val switchPreference = preference as SwitchPreference
                    val intent = activity!!.intent
                    val tempBundle = Bundle()
                    intent.putExtra("bundle", tempBundle)

                    Thread {
                        val changeTheme = newValue as Boolean

                        try {
                            activity!!.runOnUiThread {
                                switchPreference.isChecked = changeTheme
                                switchPreference.summary = "On" //this clears once I restart the activity
                                activity!!.finish()
                                activity!!.startActivity(intent)
                                activity!!.overridePendingTransition(R.anim.push_left_in, R.anim.push_left_out)
                            }
                        } catch (e: Exception) {
                            e.printStackTrace()
                        }

                        activity!!.runOnUiThread {
                            switchPreference.isEnabled = true
                        }
                    }.start()
                    false
                }

You can use layout instead: if you want to use two summaries for on and off state of switch preference you can use these properties:

<SwitchPreference
            android:summaryOff="@string/summary_off"
            android:summaryOn="@string/summary_on" />

But if you want to use Java or Kotlin: summary which is set programmatically will not be saved if you want to keep it you have to set it always in onCreate