You can easily adjust the size of the subtitles. You do that with the following steps:
1. First, start the movie or series you want to watch.
2. At the bottom right of the video screen are some buttons. Click on the button that looks like a gearwheel. A menu will appear.
3. Then click the gearwheel next to "Subtitles" again.
4. In the menu, select the size of the subtitles of your choice at "Font Size".