You can't change the Thread Name; what you do is change the Subject Box. When you go to Post to this thread, there will be a box that says Subject: Hightlight and delete what is already there, then put Lyr Add: (Title/Author if known) in that box. The colon is important. Then, when the harvesters go looking for Lyr Add it will show up.

It is also easier when using Forum Search to find the Lyr Add: posts in a whole mess of stuff about a song. Sometimes it's hard to remember to do it. I have forgotten lots of times.