Okay. For the most part, the sexual organs aren’t “switched.” People keep their own, sometimes rearranged to fit the new body shape.
The most common way that I’ve heard of for a born-male person to be reconstructed as physically female is for the sensitive bits to be turned inside out and put inside to become a vagina. I understand that there is great success retaining sensory input. In other words, it’s often still fun to have sex after the operation.
For a born-female to be surgically reconstructed as physically male is harder. Some of them do not undergo that sort of surgery at all, but have only a mastectomy. Sometimes, the hormones given to the person can make the clitoris grow – not any six inches or anything, but a large clitoris can resemble a very small penis that can be quite pleasurable to use. Or, alternatively, some tissue may be removed from the thigh area and used to construct a larger penis, but which always remains soft because it doesn’t have the same internal structure as a man’s homegrown penis – but it does fill some of the needs.
I’m not sure which of these answers is the one you were looking for, but I hope that one of them works for you. Usually people would mean a “post-op transexual male” to mean a born-female person who had phalloplasty, but since you are adding some topics that indicate you might be misunderstanding the subject, I included both.