Items in a review will always be organized and sorted by numbered headings according to the Explorer Tree hierarchy, regardless of how the review was created (from a Project, a Release, or a Filter).
What headings are and how to make them visible in the Review
Item headings are numbers which identify, in ascending order, the items’ location in the Explorer Tree. The original numbering is kept in the review while skipping the numbers of the items that were not selected to review.
When entire Sets, Folders and Components are put in review, the numbered headings are visible. When individual items are sent to review, the same order is enforced, but the numbered headings will not be displayed.
In that case, the TOC/Search view will allow reviewers to have a bit more context on the project's inherited hierarchy since it shows the sets and components where the items belong in the project.
Test Runs are an exception as they don’t have headings. Test Runs will maintain the same order as their corresponding Test Cases in a project, but numbered headings will never be displayed. Also, the TOC / Search view will appear empty unless the review contains item types other than Test Runs.
How the numbers are assigned in Explorer Tree
The base heading numbers are assigned to all top containers and start numbering down based on hierarchical levels (component, sets, items, sub-items).
These exact numbers will be reflected in a review, regardless of the review's context (e.g. items returned from a filter or the order of selection in the Project).
How to modify the review headings
Since the order of all review items is fixed based on the Explorer Tree hierarchy, the only way the heading numbers can be influenced in a review is by changing the Explorer Tree organization (e.g moving items or containers in the Project).
Please note that moves made in the Explorer Tree AFTER a review is created will affect the review as described here.