I used to have the run configuation selector in the navigation bar but when switching to the new layout the selector is gone and I can't find a setting to show it.
It used be be in the upper right navigation toolbar:
How to get the run configuration selector back with the new layout?
IntelliJ IDEA 2023.3.4 (Ultimate Edition) Build #IU-233.14475.28, built on February 13, 2024
Right-click on the main toolbar at the top and select the action to customize it:
In the dialog that opens, select the "Right" area, click +
to add a new action, search for the "Run Widget" action and click OK to add it: