What should I do for those who have changed their rank on BTT to a newbie?
What should I do to become a Jr member like before?
First off I don't think this post belongs in altcoin discussion, you would probably get much better advice if you just posted in Meta:
https://bitcointalk.org/index.php?board=24.0There is much better discussions about the current ecosystem of the forum on that board.
Secondly you need to focus more on the quality of your post and work on your english if you are not verse in it already. Don't post one sentence responses in threads where there are thousands of pages and post. You want to actually bring some substance to your post that engages others, if you are going to post in mega threads atleast post something unique and relevant to the topic or current state of the coin/project.
You will need merit to rank up, spend time reading and learning in meta board and improving your english, the more time you spend learning the better off you will be in crypto ecosystem.