Tbc chat "enter key". Please help.

Hey guys quick question for you.
Haven't played tbc before so something changed which is slightly bothering me and hoping you can help me fix it if possible.

Played expansions wotlk-mop & every time I whispered someone or they whispered me back all I had to do was hit "enter" & I would be immodestly replying back to that person.

Example:
Lets say I typed "hi" in global chat & pressed enter. Message is sent.
Now if I hit enter again 30min later it'll basically go back to typing in global chat.

Let's say I whispered someone named "lion" and pressed enter. Message is sent.
Next time I press enter I am immediately going to whisper that same person again unless I type /s or /6 /5 /4 etc ... to change it.

This is perfect as you don't have to keep changing if you want to stay in that channel or whisper same person.
If you want to change only then you have to change the code to /s or /6 etc..


Issue in tbc:
It doesn't let me use enter in the same manner stated above.
So, if I whispered someone named "lion" and pressed enter. Message is sent.
Next time I press enter it automatically takes me back to normal chat (/s). This is frustrating because every time you want to type in the same channel/whisper u did before u would have to re-type in their name or channel number etc ...

How do I make it work like wotlk-mop?


Thanks!