Since it apparently solved your issue, I'll move my comment to the answer section:
As you can see in the first screenshot the Units property of your figure is Pixels, not Normalized. But actually, that is not relevant. The buttons and other objects have a position relative to their container. That container is very likely to be the figure. That means their Position is relative to the figure. If those are in Pixel units as well, that means their position is encoded as a specific number of pixels away from the lower left corner. If you change the Units property to Normalized for all your buttons and other objects, they will be defined as a percentage of the figure width and height.
Note that changing the Units to Normalized also means that the aspect ratio of your buttons will change if the aspect ratio of your figure changes. Note that you might have to modify the font size as well to prevent large buttons with tiny text.
NB: apply these changes through the GUIDE interface, not in the fig file directly. If you would have been handed a GUI built from code, this would be a lot easier, but now you must either recreate the fig from code, or stick to GUIDE.