First you need to edit your: profile on the screenshot:
Then click on the smiley on your keyboard (as below). Quite a smiley's choice will open, select your favorite and click "Save" to confirm.
All the "difficulty" of this trick is to know that it does not work with all smiley's iPhone. Example: with this smiley, it does not work:
When the recording is done, the smiley necessarily appear as such can see in the screenshot below:
So remember to check if your smiley was displayed next to your nickname.
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