Beyond sending and reacting, every chat has a few quality-of-life tools: themes to make it look like yours, stars to keep track of the important bits, and forwarding to pass a message along. All three live in two menus: the ⋮ menu in the chat header, and the menu you get by long-pressing a message (right-click on desktop).
Chat themes
Open the ⋮ menu in the chat header and tap Chat theme. There are 24 presets across three styles, Solid (single hue, calm and clean), Gradient (two- or three-stop backgrounds), and Pattern (subtle textures behind the bubbles), each with a live preview. Tap one to apply it; tap the selected theme again to go back to the default.
Want your own? Scroll to Custom and tap Create custom: pick a start colour, an end colour, and an angle, and the bubble colour matches automatically.
A theme is set per chat, and everyone in the chat sees your choice. Pick accordingly before applying Hearts to the flatmates group.
Starred messages
Star it
Long-press the message (right-click on desktop) and tap Star. The address, the door code, the "I'll bring the cake" promise. Unstar from the same menu.
Find it again
Open the chat header's ⋮ menu and tap Starred messages. Toggle between This chat and All chats to see stars from just this conversation or every conversation you're in.
Jump to it
Tap a starred message and PopIn scrolls the chat right to it, even in another conversation.
Forwarding
Long-press a message and tap Forward. The Forward to… picker opens with a search box and your conversations, tick as many as you like and tap Forward to send it to all of them at once. The copy lands with a small Forwarded label so nobody mistakes it for your own words.
The same menu holds quick reactions, Reply, Copy, Edit, Pin, and delete options. For those, see Reactions, replies, and pins. Group housekeeping lives in Managing group chats.