Galaxy A3 - Whatsapp messages: message details shown - how to disable/change?

I recently updated my phone's software and now all of a sudden my phone shows the details of my Whatsapp messages (E.g. "Haha, yeah, I miss you too") instead of just saying, "New message received from [person's name]" on the notification panel. This is a huge inconvenience for me because if someone else is viewing something on my phone, they can see what people have sent when a message comes through, because the details show. I don't want that. Why has it changed, and how can I change it back to how it was before?