I don’t think I understand your question.
But let me clarify the use of the joker. Maybe this will answer your question.
A player in the pool gets one joker. This joker can be placed next to a match to double the points for that match.
The joker may be placed and/or moved to other matches as long the matches are still changeable. A joker is activated at the moment the match it is placed on is no longer changeable. And once activated the joker cannot be moved.
If this doesn’t answer your question, or if you encountered a bug, please give some more information.