Issues with some h files and executables in my project c++


I am working on a project and within that project I have two executables : theo1 and theo3 .

in the first one I coded h and cpp files called fancytext and fixedtext (both h and cpp as you can see in theo1) but when I am using both fancytext.h and fixedtext within theo3 an error popped up : 



within polimorphicvector I use fancytext.h and fixedtext.h but I got that error, why is that ? Should I code polymorphicvector in executable theo1 or theo3 ? 




If you want to use classes/functions/etc. from fancytext.cpp/fixedtext.cpp in polymorphicvector.cpp, you need to add to the corresponding target (theo3).