The thing to know is "shared parameters" are not a project level object. You can not use them on sheets as a project wide label. They are instance based only and you must edit the sheet view not the sheet to fill in the data.
To achieve a project wide value you must consider creating a project sheet family that you enter all project wide data with "dumb" text. You then use shared parameters for your office specific sheet data that will change on each sheet. This combination of labels and text will get you where you need to go. Use a copy of the office standard sheet to start a project then add the sheet data and project data, then import into your project. Any changes, require an edit of the project sheet file, then a reload.
For what it is worth, it is very easy to swap out sheets on a global level using the Families group in the Project Browser. As you progress through your project's phases, you can move from one sheet family to another easily as long as they use the same template origin, this way the sheet will land in same place when you switch.