Galaxy S6: received timestamp but not sent timestamp?

[AC Question]

On my Samsung S3 I had before, the time stamp shows when the sender sent the message. On my Samsung S6, the timestamp is when I received the message.

I couldn't sleep so I turned my phone on. I thought I received a goodnight message at that moment but she sent it 4 hours ago.

How do I set it so the timestamp shows when the sender sent the message instead the timestamp of me receiving the message?