Set Password does not work with BuddyPress

Today, I activated BuddyPress, then I noticed that the Set Password does not work properly.

During registration, users can enter the password, but after clicking the finish button, system will generate a random password. How to solve that?

In addition, I used "Captcha by BestWebSoft" which worked fine for registration/logon. But similar like the issue above, after BuddyPress activation, it just disappeared from the registration form. I think it is very like the same issue or at least related to the issue.