Although I can't claim to having seen every possible way to option subtitles on a TV, I have a lot of doubt that "switching a red a yellow cord" makes any sense. If it does, I stand corrected but would be interested in the details.
Otherwise, here's the reality of Spanish subtitles: you can only get it at all if the program is sending it, and not all programs do. Probably only a minority. For most TVs like yours, if the Spanish is being sent, it will show up on one of your CC options, and you'd have to try them all to see if any of them do it.
Buena suerte.
