What if an Android smartphone had the ability to choose its own sound for incoming messages, but then disappeared (details inside)?

Question

Android

That is, at the bottom of the list of built-in melodies of the smartphone there was a button "Choose your own" (or something like that) and when it was pressed, a window appeared where it was proposed to choose a method (program) with which you can select your melody. There was a choice of Total Commander, something built into Android, and something else. I chose the program built into Andoid and that's it, as a result, I could not select any of my melody with it, and the "Choose your own" button (or something like that) at the bottom of the list of smartphone's built-in melodies disappeared. What to do, how to return this button?

The same behavior in Android is where you can choose your ringtone for incoming calls. There, too, it was proposed to choose a program. I chose Total Commander and that's it, when you click on the "Choose your" button (or something like that) at the bottom of the list of built-in melodies of the smartphone, Total Commander is now immediately launched. How to choose another program? How to reset this association so that the choice of programs appears again?