I tested [wpmem_profile] : same problem, nothing happens when i fill the form.
I’m looking to give the possibility to the users to create a password before logging in.
This second instance is different from the first question you noted. Perhaps there’s a misunderstanding of the process here.
If what you want is for users to create a password before logging in (i.e. during registration), you need to add a password field to the registration process. The plugin installs some default fields when you start (any of which you may delete if not being used) and one of these is password. There is also a confirm password field for handling password comparison validation. Enable those and users can set a password when they register.
If, however, your question is really that you want users who forgot a password to be able to create a new one before logging in – the process does not work that way (and never will). If a user forgets their password, there is no way to retrieve it – passwords are hashed. In this case, a password must be reset. In order for that to happen, the user must identify themselves to receive a new password to log in. Once that occurs, they may change there password as needed. But allowing them to do that before logging in would be an insecure process.