I find the "Current executable" selection in Projects -> Build Settings -> Build Steps -> Targets quite handy.

During the upgrade to QtC 4.13 it is now possible to select multiple targets which is quite handy, but this selection is not persistent and quite often reset to the default target "all". It is not persistent over restarts which was previously the case but it also resets quite often during an instance run. I think it is everytime I change something in my CMakeLists.txt