When you install QtCreator on MAC OS X you can find it in
/applications/qt
in this folder there is another folder called
5.2.1
Here there are all the compilers.
So to solve the issue you can either add, in QtCreator options, the path of every qmake.bin file or cut the 5.2.1 folder and paste in
/Users/YOURNAME/qt
creating qt folder if it doesn't exist.
PS: I've tried to make the directory invisible, but if I do so, I get errors using the second method