Why do some threads close 6 days after the last post while other threads close only 3 days after the last post?
You have an example? It’s most likely a difference in the configuration for that subgroup
The thread I started about my favorite songs says “This topic will close 3 days after the last reply.”
Humor was set to close after 3. I changed it to 7.
That means 7 days after the last post it will close.
Thank you for the explanation, as well as the modification 
No problem