JSFiddle - React, Tailwind, and code Playground

JavaScript

var yourString = "sss your string 'this is safe' and this is not";

var tokens = yourString.split("");
var inQuotes = false;
for(var i=0;i<tokens.length;i++){
    if(tokens[i] == "'"){
        inQuotes = !inQuotes;
    }else 
    if(!inQuotes && tokens[i] == 's'){
        tokens[i] = 'p'
    }
}

var result = tokens.join("");

document.body.innerHTML = result;