Excuse me @sam and the rest of team. 
Is there some possibly to see a “log” for solved events?
An example:
User “A” opened a topic.
User “B” replayed
User “C” replayed
User “A” said thanks for the info.
Topic “solved”. (But I did not know who mark the message as solved)
Users A, and B are normal users (trust level 2).
Only “C” is trust level 4 (leader).
And leaders could mark a solved message.
How can I (staff) see if the user “C” made solved their own message?