How to set required fields in User Profiles.

How do we set required fields in the users' profiles?
For example, we want all of our users to fill in their location.
Thanks!

Acp>users&groups>profiles> location
then presses the gear you should see a box that says Necessarily filled ?
press the dot next to yes then choose save then its a required feild now!

Thanks so much! Didn't realize about the gears, but now I know.

Here's one more question:
Still using the example of Location, if I apply a change now, what will happen to all the users who have registered without filling in the location field?

Hello,

Still using the example of Location, if I apply a change now, what will happen to all the users who have registered without filling in the location field?

Nothing will happen or nothing will be updated on their profile unless they go and modify that field.

Only those who'll be just registering will be able to fill that necessarily on the registration page.

Thanks! This is solved.