Saving state instead of highscore

At first I'd like to apologize for my bad english, I'm form Poland :)

Here is my problem. I have my coin script and the other one, that counts number of how many I collect them in one round and then saves state as highscore. I want it to save state from all rounds like that(like a bank account):

Account = number of coins collected in all previous rounds + number of coins collected in round that I just finished

Here is my script that I'm using for collecting and saving higscore. What I have to do to create account instead of highscore?

using UnityEngine; using System.Collections; using UnityEngine.UI;

public class ScoreSystemCS : MonoBehaviour {

 public static int myScore; 
 public int highScore1;
 
 
 Text scoreText1;
 Text highText1;
 
 
 public void Start(){ 
     
     myScore = 0; 
     
     highScore1 = PlayerPrefs.GetInt("HighScore1",0);
     
     scoreText1 = GameObject.Find ("scoreText1").GetComponent<Text>();
     highText1 = GameObject.Find ("highText1").GetComponent<Text>();
 }
 
 public void Update(){
     
     
     scoreText1.text = ("myScore: " + myScore);
     
     highText1.text = ("Account: " + highScore1);
     
 }
 
 public void CheckHighscore(){
     
     if (myScore > highScore1) {
         Debug.Log ("Saving Score");
         
         PlayerPrefs.SetInt ("HighScore", myScore);
     }
 }
 

}