To change WhatsApp chat themes, go to Settings > Chats > Default chat theme and pick from preset themes or upload a custom ...

WhatsApp is introducing Chat themes, allowing users to customize chat bubbles and backgrounds. Users can choose from 8 preset themes or customize their own for individual conversations.

Starting today, WhatsApp will provide multiple chat theme options for both iOS and Android users, so that they can make chats unique with “colorful chat bubbles and new wallpapers.” ...

WhatsApp is rolling out new chat themes, enabling you to customize your in-stream chats with colorful backgrounds, alternative chat bubbles, and more. Which, apparently, has been a much-requested ...