Only you see the new name
This custom label only changes what you see in your own chat list and conversation β the other person's profile, and how they appear to everyone else, is completely unaffected.
Works for one-on-one chats, not just groups
This is different from renaming a group, which every member sees. A private display name applies to an individual conversation and stays visible only on your own device.
Frequently Asked Questions
Does the other person know I changed their display name?
No β a private display name is visible only to you and is never shown to the other person or synced to their device.
Can I do this for a one-on-one chat, not just a group?
Yes β this feature works on individual conversations too, letting you label them independently of both the group-naming feature and the other person's own profile name.