If I want an extra field to be visible in the block "New Members" and eventually in other modules.
I would copy the template to the themes folder and edit in the template for the module. In the case with new members i would edit in
system_block_newusers.html
In the file there is a <{$user.joindate}>
Where do I change, so I can use <{$user.abcd}>
abcd is an extra field from the profile module.