How To Add Qr Option To Already Created Galleries

Im a newbie. My friend helped me create galleries. I have school portrait gallery>each school

I need to add the QR codes option. I can't figure out where that is to add it to my galleries already created. 

Im not seeing these options or windows. 

That means the section you created that you are adding a gallery to wasn't created as a "Client galleries / selling photos." section so it won't have that option.  (or you are creating a top level page which won't have that option).

Edit the section you created and in the Content Function area select "Client galleries / selling photos." and save. Then you will have that option when creating galleries in that section.