I am not sure about how this Forum works but mostly what I have seen is only people with Moderators or Admin profile can close a Thread/Topic. [This is in case of WordPress forums which you create using plugins].
Also at some forums even after the Threads/Topics are closed, the Admins and mods are still able to add comments/posts to it or can open the Topic again so this might cause some problems if someone re-opens a topic.
Further, it would be great if only Admins exercise this power as some new users would close the thread or Topic immediately when they get a solution. In the past, There have been times on this Forum when members posted their questions and immediately posted a comment saying their issue was solved. So, they might close the Topic even before anyone contributes their thoughts under the topic.
And probably this might require a new set of rules to be written that must be followed by all the members to effectively close the Topics.
[This is what I have noticed on other forums. And I am unaware about the working of this one]. Mustafa sir can explain us better.
Talking about the bug you reported, That might not be a bug. I too didn't get TL3 even after the pre-requisites were satisfied. But later I did. And what rights you get can probably be controlled by the Admins. Wait till you get to hear something from them.
I make my words/sentences BOLD by first selecting the text and then hitting the 'B' Button. Or Hit the 'B' Button and then edit the words in between the double "*". And it works just fine.
~ Rohan Chaubey.