Border Styles are always a fixed size regardless of the size of the template. So if you put say a "1/4 inch wide double matt" style on a 8x8 sized layout, it will look proportionately bigger then the same style on a 24x24 sized layout.

To see what the style will really look like on your layout, use the "Bigger Size" or "Smaller Size" buttons to get the layout to the size that you want (look at the bottom of the screen for the current size) or view the layout in Select Size View.

Also make sure that you are viewing the layouts with the sizing method that you intend to order or produce the layout. This is selected in the View menu and can be Show Layouts in Traditional Matted Sizes or Show Layouts as Composite Sizes.  Since these will change the way the layout is sized, they will change the relative appearance of any applied border styles.