Votes will only come in once the presentation is in presentation modes and you are on the voting slide. From that moment votes will come in automatically. On this moment voting is possible. Once you go to the next slide the lines will close again. When you have multiple questions behind each other for your audience, this will not cause any problems. When you go to the next slide the lines of slide one will close and the lines of the next slide will open. The results are only visible once the presentation is in presentation modes.