FLStudio will look for the FLStudio engine. Normally this is the location of FLStudio that was most recently installed. You may want to use another installation of FLStudio, for example an Alpha or Beta for testing ...
FLStudio and my third party plugins (East West Quantum Leap PLAY, Sylenth, Dexed and a few other VSTs/Plugins), open my projects and they play exactly the same.
I am currently using FLStudio 12. I know I need to move ...