random message every x seconds but to stay on screen for a few seconds

I have a program where I am displaying a message every x seconds (the message pops up), is there a way for the message to stay a little bit on the screen, because there is no time for the user to read it properly.

your guidance is much appreciated.

below is a piece of my code where I am using millis().

if (millis() - timer >= 4000) //random message every 4 seconds
      {
        if(user11.equals(rev_film1[0]))
        {
          app.text(user11, 15,490);
          app.text(rat_film1[0] + " / 10",100,550);
          timer = millis();
        }
        else if(user11.equals(rev_film1[1]))
        {
          app.text(user11, 15,490);
          app.text(rat_film1[1] + " / 10",100,550);
          timer = millis();
        }
        else if(user11.equals(rev_film1[2]))
        {
          app.text(user11, 15,490);
          app.text(rat_film1[2] + " / 10",100,550);
          timer = millis();
        }
        else if(user11.equals(rev_film1[3]))
        {
          app.text(user11, 15,490);
          app.text(rat_film1[3] + " / 10",100,550);
          timer = millis();
        }
      }