Scripts, measures, dimensions, master visualizations, sheets, stories and Bookmarks are constraint to an app only. Where as the Data connections, visualizations, extension objects are global.
Its not possible to make measures, dimensions, master visualizations, sheets, stories and Bookmarks global but... you can make the script partially global.
1) create a folder connection to a new folder on your server and call it Scripts.
2) Create text files and save your scripts in that folder.
3) Now you can make use of the include statement in your load script editor to read the text files.
This is just a work around.