Sorry for the trouble @Patty_Crain! We changed the behavior in version 3, actually in response to years of requests and feedback. The issue we had in v2 is that if your mockups were slightly different sizes, such as with variable heights, then it would jump all around in fullscreen mode. There was no anchor—each mockup was centered horizontally and vertically.
With version 3, we take the largest mockup in your project, and center that horizontally and vertically. That creates the anchor point for the top left corner. We display all other mockups with the top left corner matching the largest mockup. That way, navigation links don’t jump around, and it is a predictable experience.
I’m guessing that is the issue that you are running into, and that it’s not working out well for you. One thing you could do is to edit down your largest mockup, and maybe break it up over multiple mockups so that it’s not so large. That way, you could get the average size to be the largest and have a more consistent experience in fullscreen.
We’re hoping that once people learn this new way, it will be much better for them. We really appreciate hearing your feedback on it though!