I definitely need help with this before I do something embarrassing!
Sometimes when I open a text messaging thread and reply, the message doesn't go to that contact... it *looks* as if it did, and shows up in that thread, but when I look at details I can see that it actually went to someone I messaged previously.
For example, a reply to a friend's message went to Twitter. Another ended up going to the wrong friend, confusing her AND the person who was expecting the response!
It doesn't always happen, but I don't know why or why not...The only way I've found so far to be SURE a message goes to the right place is to exit the thread and start a new one, selecting the correct contact.
I've had the phone only 4 days, and it is my first smartphone, so please be gentle with me!