Current status
In test plans (and test runs) all test cases are sorted first by their folder and then any other sorting criteria.
Also see: Is is possible to order test cases in a test plan/run - Support - Testiny Forum
Why the request is relevant
Often, folders are used to collect test cases by topics. In test plans, test cases from many different folders may be collected. During the test run, the order in which the test cases are tested might be crucial.
Feature request
The order of test cases in a test run and test plan should be manually adjustable.
This request builds upon the existing feature request Show test cases in test run without folders - App Feedback - Testiny Forum
Example
In our case, folders represent processes. Test cases cover different process variants und sub-processes. Test plans are used to string together many sub-processes and process variants. They represent end-to-end processes which jump between different processes and include loops back to “former” processes. As a result, it is necessary to order the test cases regardless of their folder.

That is correct. A change according to my feature request would significantly add value to test plans in all cases where the order of test cases is relevant.
– Paul_HeinSimilar need, different angle: we want to share test cases between QA and UAT plans rather than duplicate them. QA order is thoroughness-driven; UAT order follows the user journey — same cases, different logical order per plan. Right now we either pick one global order or duplicate cases per plan, which is the exact overhead we're trying to avoid by sharing them. +1 for a per-plan override — even simple manual reordering scoped to one plan, leaving the global folder order untouched, would solve this.
– Emily_Larkin-Jefferies