I have 2 frames. I switch the buffer in first frame to buffer A. When I try to switch the buffer in the second frame to buffer A, Emacs brings the first frame forward. What I want is to open buffer A in both frames. Is there a setting that makes Emacs bring the other frame forward when buffer A is already opened in it?
That is a feature of “Ido”, which you seem to be using.
Just go to “Customize Emacs”, and in the group “Convenience / Ido”, change the settings “Ido Default Buffer Method” and “Ido Default File Method”, which surely are now set to “Raise frame if already shown”.