You can only select one create scope.
You can select multiple query scopes, which allows you to search across multiple plants or projects. The results are displayed on tabs in alphabetical order corresponding to each selected configuration.
You can also select a project as your query scope. When you select a project, the query returns objects found in both the project and the plant. For example, if you set your query scope as Project 2 of PlantA, then your query returns objects that exist in both Project 2 and PlantA.