To customize each chat individually, click the chat name at the top of the chat screen (on iOS), or click the 3-dot menu (on Android) > Chat theme.
Once the update arrives on your phone, you'll be able to head to the settings menu and change your chat bubbles and background to any colour you fancy rather than being stuck with WhatsApp's famous green shade.
Along with new Chat Themes, WhatsApp has also added new wallpapers as well.
You can also pick from one of WhatsApp's pre-set chat themes, which changes your background and bubbles, or mix and match colours depending on your mood.
This basically lets you make your chats more unique with simple ways to switch up the colourful chat bubbles and add new wallpapers.