How to add score to scoreboard?

I am making a simple game, it is my first project with JavaScript. So You click the button, it gives You and Computer a math randoms, the winner is the one with bigger number. I created a scoreboard and want to add score whetever someone wins. The problem is that it doesnt work, could You please give me some solutions?

 function addScore() {
  let userResult = Number(document.getElementById("userNumber"));
  let compResult = Number(document.getElementById("computerNumber"));
  let userScore = Number(document.getElementById("userScore"));
  let computerScore = Number(document.getElementById("compScore"));
  if (userResult > compResult) {
    userScore = userScore.innerHTML =+ 1;
  } else if (userResult < compResult) {
    computerScore = computerScore.innerHTML =+ 1;
  }
}