Reset Password functionality not working

The site I am working on was made using wordpress. A custom registration module was made. There are two problems:

When I reset the password, the mail “From” name says WordPress instead of a custom name. i want to be able to change that.

Is there a default file that could control this? Somewhere in the themes folder?

I have something like this in my wp-login file in the themes folder:

$title = apply_filters(‘retrieve_password_title’, $title);

What does this mean?