List of unresolved threads getting longer and longer

Could you explain how I mark a thread of mine as resolved please?

I was trying to do this a couple of days ago and couldn’t see how. I’m using an iPhone if that makes a difference.

“Thread is unresolved” appears near the top of the page, but tapping on it does nothing. “Edit Thread” only brings up an option to change the title. I can edit the body text of my posts by tapping on edit there, but “mark thread as resolved” - I can’t see that anywhere.

Quote from Yoda Guitar

Is there any way to mark threads as resolved automatically after some time?
Thread is Unresolved flag is set and Users are don't mark there post as resolved.

Yoda Guitar how do I mark a thread of mine as resolved?