Hi!
I have searched all topics regarding this, and I have seen that the general answer is that you do not have this functionality. Let me just add my vote to such a feature - i.e. as a payable addon.
Our use case would be for customers of us adding support tickets, and we need them to include version of software, priority and other text description fields. What this forum would be a great fit for, is to have a thread for each issue where we can comment on it and have the latest updates on it in a forum way.
Ideally, these custom fields could be edited afterwards, similar to the "solved" button you have today.
Again, I know you do not have this now, but I am hoping my (and possibly others) votes can tip you into integrating it one day 🙂
Have a nice day!