How to set optimize for speed?

I have tried to set speed optimization in the GH compiler for NET+50 under “File options for project.bld/Optimization”. When I mark the project.bld-file, I get the message: (Reading build file: “C:\Kapsch-AlcMux\NETOS5_GH35\src\apps\Ipm\project.bld”) Then I tick the alternative “Optimize for speed” in Edit mode and click on “Apply”, I get: (Checking out “C:\Kapsch-AlcMux\NETOS5_GH35\src\apps\Ipm\project.bld” from version control) I close this meny and try to save the project. At first I get a warning window saying: Project(s) contain unsaved modifications, save changes? When I choose “Yes” I get Project “C:\Kapsch-AlcMux\NETOS5_GH35\src\apps\Ipm\project.bld” could not be saved, because it could not be checked out. and the last window remains. I have to choose “No”, and then the optimization for speed is lost. Does anyone know how to set the compiler to optimize for speed? /Henric Rappe