When doing a layout I guess most users are editing dif. text ie. title etc with the text-properties in the ribbon rather than manipulating the entries in the house-style dialogbox being that they see the changes directly and can adjust the ie. size etc. until it fits their needs.
Why not adding a save-button in/at (never been sure) the ribbon - text so that they can save their changes into the house-style either as a new style or to update the style where their settings are based on....?
When closing the file a message-box will appear that there are changes in the house-style and if they should be saved. In the score these changes will stay anyway.