When working with Scripture service items, Presenter will put a slide break after each verse, meaning there will be one verse per slide. To change where the slide break occurs, go to the foreground settings on your Scripture item. There, you'll find an option for Slide Break.
You can select between various options like putting a slide break after every 10 words, 20 words, and so on. There is also an option for "Custom" which allows you to put a break after any verses of your choosing.
In the example below, the custom breaks are placed after the first two verses and after the next three verses. This means that the first slide will have two verses on it, while the next slide will have three. To add a custom break, click on the green + button next to the verse after which the break should occur. If you add a break in the wrong place, you can drag and drop it to the desired location or click the red trash can button to delete it altogether.