Specify HarmonyOS run settings
To specify settings for running applications on the Run device that you select for a kit, go to Projects > Run Settings.
The application runs on the device inside the package that was deployed to it, so there is no executable to point at and no working directory to choose. What the run configuration does carry is the arguments the application is started with, which Qt Creator passes to aa start and the application receives as its own argv.
Manage device configurations opens Preferences > Devices > Devices, where the device the kit runs on is listed.
See also How to: Develop for HarmonyOS, Developing for HarmonyOS devices, How to: Manage kits, Configure projects for running, Managing kits, and Specify HarmonyOS deploy settings.